iwlwifi: pcie: remove non-responsive device

If we fail to to grab NIC access because the device is not responding
(i.e. CSR_GP_CNTRL returns 0xFFFFFFFF), remove the device from the PCI
bus, to avoid any further damage, and to let the user space rescan.

In order to inform the userspace that a rescan is needed, we send a
kobject uevent with "INACCESSIBLE".

This functionality is disabled by default, but can be enabled via a
new module parameter called "remove_when_gone".  In the future we may
change this module parameter to include 3 modes instead: do nothing;
auto-rescan or; send uevent.

Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Signed-off-by: Rajat Jain <rajatja@google.com>