wil6210: fix for memory corruption while insmod

After setting interrupt handler, driver enabled interrupts.
This caused stale (old) HW interrupts to fire before driver is
fully initialized.
The fix is to enable interrupts only when driver is fully initialized
and after FW/HW reset (to prevent any stale interrupts)

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