ath9k: Fix NULL pointer dereference on early irq
ath9k: Fix NULL pointer dereference on early irq

The ah struct might not have been initialized when
interrupt comes so check for it.

Signed-off-by: Wojciech Dubowik <ab0ced3f706c6ddc8ad8081a340417e05e393b33@neratec.com>
Signed-off-by: John W. Linville <2a53bac7a5d324865ef46ec4c38b2c0fba1456b4@tuxdriver.com>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs