brcmsmac: Fix WARNING caused by lack of calls to dma_mapping_error()

brcmsmac: Fix WARNING caused by lack of calls to dma_mapping_error()

The driver fails to check the results of DMA mapping in twp places,
which results in the following warning:

[   28.078515] ------------[ cut here ]------------
[   28.078529] WARNING: at lib/dma-debug.c:937 check_unmap+0x47e/0x930()
[   28.078533] bcma-pci-bridge 0000:0e:00.0: DMA-API: device driver failed to check map error[device address=0x00000000b5d60d6c] [size=1876 bytes] [mapped as
 single]
[   28.078536] Modules linked in: bnep bluetooth vboxpci(O) vboxnetadp(O) vboxnetflt(O) vboxdrv(O) ipv6 b43 brcmsmac rtl8192cu rtl8192c_common rtlwifi mac802
11 brcmutil cfg80211 snd_hda_codec_conexant rng_core snd_hda_intel kvm_amd snd_hda_codec ssb kvm mmc_core snd_pcm snd_seq snd_timer snd_seq_device snd k8temp
 cordic joydev serio_raw hwmon sr_mod sg pcmcia pcmcia_core soundcore cdrom i2c_nforce2 i2c_core forcedeth bcma snd_page_alloc autofs4 ext4 jbd2 mbcache crc1
6 scsi_dh_alua scsi_dh_hp_sw scsi_dh_rdac scsi_dh_emc scsi_dh ata_generic pata_amd
[   28.078602] CPU: 1 PID: 2570 Comm: NetworkManager Tainted: G           O 3.10.0-rc7-wl+ #42
[   28.078605] Hardware name: Hewlett-Packard HP Pavilion dv2700 Notebook PC/30D6, BIOS F.27 11/27/2008
[   28.078607]  0000000000000009 ffff8800bbb03ad8 ffffffff8144f898 ffff8800bbb03b18
[   28.078612]  ffffffff8103e1eb 0000000000000002 ffff8800b719f480 ffff8800b7b9c010
[   28.078617]  ffffffff824204c0 ffffffff81754d57 0000000000000754 ffff8800bbb03b78
[   28.078622] Call Trace:
[   28.078624]  <IRQ>  [<ffffffff8144f898>] dump_stack+0x19/0x1b
[   28.078634]  [<ffffffff8103e1eb>] warn_slowpath_common+0x6b/0xa0
[   28.078638]  [<ffffffff8103e2c1>] warn_slowpath_fmt+0x41/0x50
[   28.078650]  [<ffffffff8122d7ae>] check_unmap+0x47e/0x930
[   28.078655]  [<ffffffff8122de4c>] debug_dma_unmap_page+0x5c/0x70
[   28.078679]  [<ffffffffa04a808c>] dma64_getnextrxp+0x10c/0x190 [brcmsmac]
[   28.078691]  [<ffffffffa04a9042>] dma_rx+0x62/0x240 [brcmsmac]
[   28.078707]  [<ffffffffa0479101>] brcms_c_dpc+0x211/0x9d0 [brcmsmac]
[   28.078717]  [<ffffffffa046d927>] ? brcms_dpc+0x27/0xf0 [brcmsmac]
[   28.078731]  [<ffffffffa046d947>] brcms_dpc+0x47/0xf0 [brcmsmac]
[   28.078736]  [<ffffffff81047dcc>] tasklet_action+0x6c/0xf0
--snip--
[   28.078974]  [<ffffffff813891bd>] SyS_sendmsg+0xd/0x20
[   28.078979]  [<ffffffff81455c24>] tracesys+0xdd/0xe2
[   28.078982] ---[ end trace 6164d1a08148e9c8 ]---
[   28.078984] Mapped at:
[   28.078985]  [<ffffffff8122c8fd>] debug_dma_map_page+0x9d/0x150
[   28.078989]  [<ffffffffa04a9322>] dma_rxfill+0x102/0x3d0 [brcmsmac]
[   28.079001]  [<ffffffffa047a13d>] brcms_c_init+0x87d/0x1100 [brcmsmac]
[   28.079010]  [<ffffffffa046d851>] brcms_init+0x21/0x30 [brcmsmac]
[   28.079018]  [<ffffffffa04786e0>] brcms_c_up+0x150/0x430 [brcmsmac]

As the patch adds a new failure mechanism to dma_rxfill(). When I changed the
comment at the start of the routine to add that information, I also polished
the wording.

Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
Cc: Stable <stable@vger.kernel.org>
Cc: Brett Rudley <brudley@broadcom.com>
Cc: Franky (Zhenhui) Lin <frankyl@broadcom.com>
Cc: Hante Meuleman <meuleman@broadcom.com>
Cc: brcm80211-dev-list@broadcom.com
Acked-by: Arend van Spriel <arend@broadcom.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>