wifi: iwlwifi: pcie: fix possible NULL pointer dereference

In the Linux kernel, the following vulnerability has been resolved:

wifi: iwlwifi: pcie: fix possible NULL pointer dereference

It is possible that iwl_pci_probe() will fail and free the trans,

then afterwards iwl_pci_remove() will be called and crash by trying

to access trans which is already freed, fix it.

iwlwifi 0000:01:00.0: Detected crf-id 0xa5a5a5a2, cnv-id 0xa5a5a5a2

wfpm id 0xa5a5a5a2

iwlwifi 0000:01:00.0: Can't find a correct rfid for crf id 0x5a2

...

BUG: kernel NULL pointer dereference, address: 0000000000000028

...

RIP: 0010:iwl_pci_remove+0x12/0x30 [iwlwifi]

pci_device_remove+0x3e/0xb0

device_release_driver_internal+0x103/0x1f0

driver_detach+0x4c/0x90

bus_remove_driver+0x5c/0xd0

driver_unregister+0x31/0x50

pci_unregister_driver+0x40/0x90

iwl_pci_unregister_driver+0x15/0x20 [iwlwifi]

__exit_compat+0x9/0x98 [iwlwifi]

__x64_sys_delete_module+0x147/0x260