wil6210: fix for memory corruption upon rmmod

Driver disabled PCI master before making sure HW is idle.
This caused memory corruption in case HW access system memory after
PCI master got disabled.
The fix is to change uninit sequence. Make sure FW/HW is idle before
disabling PCI

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>