ENGR00287512 net:fec: fix WARNING caused by lack of calling dma_mapping_error()

ENGR00287512 net:fec: fix WARNING caused by lack of calling dma_mapping_error()

Enable CONFIG_HAVE_DMA_API_DEBUG, the kernel dump warning:

------------[ cut here ]------------
WARNING: at lib/dma-debug.c:937 check_unmap+0x43c/0x7d8()
fec 2188000.ethernet: DMA-API: device driver failed to check map
error[device address=0x00000000383a8040] [size=2048 bytes] [mapped as single]

Modules linked in:
CPU: 0 PID: 0 Comm: swapper/0 Not tainted 3.10.17-16827-g9cdb0ba-dirty #188
[<80013c4c>] (unwind_backtrace+0x0/0xf8) from [<80011704>] (show_stack+0x10
[<80011704>] (show_stack+0x10/0x14) from [<80025614>] (warn_slowpath_common
[<80025614>] (warn_slowpath_common+0x4c/0x6c) from [<800256c8>] (warn_slowp
[<800256c8>] (warn_slowpath_fmt+0x30/0x40) from [<8026bfdc>] (check_unmap+0
[<8026bfdc>] (check_unmap+0x43c/0x7d8) from [<8026c584>] (debug_dma_unmap_p
[<8026c584>] (debug_dma_unmap_page+0x6c/0x78) from [<8038049c>] (fec_enet_r
[<8038049c>] (fec_enet_rx_napi+0x254/0x8a8) from [<804dc8c0>] (net_rx_actio
[<804dc8c0>] (net_rx_action+0x94/0x160) from [<8002c758>] (__do_softirq+0xe
[<8002c758>] (__do_softirq+0xe8/0x1d0) from [<8002c8e8>] (do_softirq+0x4c/0
[<8002c8e8>] (do_softirq+0x4c/0x58) from [<8002cb50>] (irq_exit+0x90/0xc8)
[<8002cb50>] (irq_exit+0x90/0xc8) from [<8000ea88>] (handle_IRQ+0x3c/0x94)
[<8000ea88>] (handle_IRQ+0x3c/0x94) from [<8000855c>] (gic_handle_irq+0x28/
[<8000855c>] (gic_handle_irq+0x28/0x5c) from [<8000de00>] (__irq_svc+0x40/0
Exception stack(0x815a5f38 to 0x815a5f80)
5f20:                                                       815a5f80 3b9aca
5f40: 0fe52383 00000002 0dd8950e 00000002 81e7b080 00000000 00000000 815ac4
5f60: 806032ec 00000000 00000017 815a5f80 80059028 8041fc4c 60000013 ffffff
[<8000de00>] (__irq_svc+0x40/0x50) from [<8041fc4c>] (cpuidle_enter_state+0
[<8041fc4c>] (cpuidle_enter_state+0x50/0xf0) from [<8041fd94>] (cpuidle_idl
[<8041fd94>] (cpuidle_idle_call+0xa8/0x14c) from [<8000edac>] (arch_cpu_idl
[<8000edac>] (arch_cpu_idle+0x10/0x4c) from [<800582f8>] (cpu_startup_entry
[<800582f8>] (cpu_startup_entry+0x60/0x130) from [<80bc7a48>] (start_kernel
[<80bc7a48>] (start_kernel+0x2d0/0x328) from [<10008074>] (0x10008074)
---[ end trace c6edec32436e0042 ]---

Because dma-debug add new interfaces to debug dma mapping errors, pls refer
to: http://lwn.net/Articles/516640/

After dma mapping, it must call dma_mapping_error() to check mapping error,
otherwise the map_err_type alway is MAP_ERR_NOT_CHECKED, check_unmap() define
the mapping is not checked and dump the error msg.

So, and dma_mapping_error() checking to fix the WARNING.

Signed-off-by: Fugang Duan  <B38611@freescale.com>