iwlwifi: cancel scan watchdog in iwl_bg_abort_scan

iwlwifi: cancel scan watchdog in iwl_bg_abort_scan

Avoids this:

WARNING: at net/mac80211/scan.c:312 ieee80211_scan_completed+0x5f/0x1f1
[mac80211]()
Hardware name: Latitude E5400
Modules linked in: aes_x86_64 aes_generic fuse ipt_MASQUERADE iptable_nat
nf_nat rfcomm sco bridge stp llc bnep l2cap sunrpc cpufreq_ondemand
acpi_cpufreq freq_table xt_physdev ip6t_REJECT nf_conntrack_ipv6
ip6table_filter ip6_tables ipv6 kvm_intel kvm uinput arc4 ecb
snd_hda_codec_intelhdmi snd_hda_codec_idt snd_hda_intel iwlagn snd_hda_codec
snd_hwdep snd_seq snd_seq_device iwlcore snd_pcm dell_wmi sdhci_pci sdhci
iTCO_wdt tg3 dell_laptop mmc_core i2c_i801 wmi mac80211 snd_timer
iTCO_vendor_support btusb joydev dcdbas cfg80211 bluetooth snd soundcore
microcode rfkill snd_page_alloc firewire_ohci firewire_core crc_itu_t
yenta_socket rsrc_nonstatic i915 drm_kms_helper drm i2c_algo_bit i2c_core video
output [last unloaded: scsi_wait_scan]
Pid: 979, comm: iwlagn Tainted: G        W  2.6.33.3-85.fc13.x86_64 #1
Call Trace:
[<ffffffff8104b558>] warn_slowpath_common+0x77/0x8f
[<ffffffff8104b57f>] warn_slowpath_null+0xf/0x11
[<ffffffffa01bb7d9>] ieee80211_scan_completed+0x5f/0x1f1 [mac80211]
[<ffffffffa02a23f0>] iwl_bg_scan_completed+0xbb/0x17a [iwlcore]
[<ffffffff81060d3d>] worker_thread+0x1a4/0x232
[<ffffffffa02a2335>] ? iwl_bg_scan_completed+0x0/0x17a [iwlcore]
[<ffffffff81064817>] ? autoremove_wake_function+0x0/0x34
[<ffffffff81060b99>] ? worker_thread+0x0/0x232
[<ffffffff810643c7>] kthread+0x7a/0x82
[<ffffffff8100a924>] kernel_thread_helper+0x4/0x10
[<ffffffff8106434d>] ? kthread+0x0/0x82
[<ffffffff8100a920>] ? kernel_thread_helper+0x0/0x10

Reported here:

	https://bugzilla.redhat.com/show_bug.cgi?id=590436

Signed-off-by: John W. Linville <linville@tuxdriver.com>
Reported-by: Mihai Harpau <mishu@piatafinanciara.ro>
Cc: stable@kernel.org
Acked-by: Reinette Chatre <reinette.chatre@intel.com>