iwlwifi: save PCI state before suspend, restore after resume

This is the right thing to do and fixes the following warning:

[  115.012278] ------------[ cut here ]------------
[  115.012281] WARNING: at drivers/pci/pci-driver.c:370
pci_legacy_suspend+0x85/0xc2()
[  115.012285] Hardware name: Latitude D630
[  115.012301] PCI PM: Device state not saved by
iwl3945_pci_suspend+0x0/0x4c [iwl3945]
[  115.012304] Modules linked in: fuse nfsd lockd nfs_acl auth_rpcgss
exportfs sunrpc ipv6 acpi_cpufreq kvm_intel kvm snd_hda_codec_idt
snd_hda_intel snd_hda_codec snd_hwdep arc4 snd_seq_device snd_pcm_oss
snd_mixer_oss ecb snd_pcm cryptomgr aead snd_timer crypto_blkcipher
snd snd_page_alloc ohci1394 crypto_hash crypto_algapi ch341 ieee1394
usbserial thermal iwl3945 mac80211 led_class lib80211 tg3 processor
i2c_i801 i2c_core sg cfg80211 libphy usbhid battery ac button sr_mod
cdrom evdev dcdbas ata_generic ata_piix libata sd_mod scsi_mod ext3
jbd mbcache uhci_hcd ohci_hcd ehci_hcd usbcore [last unloaded:
microcode]
[  115.012374] Pid: 4163, comm: pm-suspend Not tainted
2.6.29-rc3-00227-gf1dd849-dirty #67
[  115.012377] Call Trace:
[  115.012382]  [<ffffffff8023d04d>] warn_slowpath+0xb1/0xed
[  115.012387]  [<ffffffff80450b5e>] ? _spin_unlock_irqrestore+0x5c/0x78
[  115.012390]  [<ffffffff80254f08>] ? up+0x34/0x39
[  115.012394]  [<ffffffff80362319>] ? acpi_ut_release_mutex+0x5d/0x61
[  115.012397]  [<ffffffff803584b2>] ? acpi_get_data+0x5e/0x70
[  115.012400]  [<ffffffff80363dd9>] ? acpi_bus_get_device+0x25/0x39
[  115.012403]  [<ffffffff80363e98>] ? acpi_bus_power_manageable+0x11/0x29
[  115.012406]  [<ffffffff803462f7>] ? acpi_pci_power_manageable+0x17/0x19
[  115.012410]  [<ffffffff8033ddfd>] ? pci_set_power_state+0xcc/0x101
[  115.012418]  [<ffffffffa01f28e9>] ? iwl3945_pci_suspend+0x0/0x4c [iwl3945]
[  115.012422]  [<ffffffff803401e6>] pci_legacy_suspend+0x85/0xc2
[  115.012425]  [<ffffffff80340316>] pci_pm_suspend+0x34/0x86
[  115.012429]  [<ffffffff8039d7ce>] pm_op+0x52/0xe5
[  115.012432]  [<ffffffff8039dd78>] device_suspend+0x32a/0x451
[  115.012436]  [<ffffffff80269ec2>] suspend_devices_and_enter+0x3e/0x13a
[  115.012439]  [<ffffffff8026a128>] enter_state+0x110/0x164
[  115.012442]  [<ffffffff8026a233>] state_store+0xb7/0xd7
[  115.012446]  [<ffffffff8032f95f>] kobj_attr_store+0x17/0x19
[  115.012449]  [<ffffffff80307d64>] sysfs_write_file+0xe4/0x119
[  115.012453]  [<ffffffff802baa7a>] vfs_write+0xae/0x137
[  115.012456]  [<ffffffff802babc7>] sys_write+0x47/0x70
[  115.012459]  [<ffffffff8020b73a>] system_call_fastpath+0x16/0x1b
[  115.012467] ---[ end trace 829828966f6f24dc ]---

Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Tested-by: Ming Lei <tom.leiming@gmail.com>
Cc: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: John W. Linville <linville@tuxdriver.com>