The firmware needs to be stopped quickly (100ms) after the
RFKILL interrupt fired. Failing to do so would allow the
firmware to access the radio registers which would lead to
a hardware error.

Before this change, we would kill the firmware only when
mac80211 stops the device which can take a fair amount of
time. Take a shortcut by stopping the device right away
in the interrupt.

This is not relevant if the current firmware is INIT
firmware since that firmware can run while in RFKILL.
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>