wil6210: Detect FW error

In the firmware, added is ability to report internal errors using IRQ.

Catch this IRQ and notify user space via netlink

User space get notified like (udevadm monitor --kernel --property):

KERNEL[12660.320520] change   /devices/pci0000:00/0000:00:1c.1/0000:02:00.0/0000:03:01.0/0000:05:00.0/net/wlan12 (net)
ACTION=change
DEVPATH=/devices/pci0000:00/0000:00:1c.1/0000:02:00.0/0000:03:01.0/0000:05:00.0/net/wlan12
DEVTYPE=wlan
EVENT=FW_ERROR
IFINDEX=6
INTERFACE=wlan12
SEQNUM=2489
SOURCE=wil6210
SUBSYSTEM=net

Signed-off-by: Vladimir Kondratiev <qca_vkondrat@qca.qualcomm.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>