ath9k: initialize hw prior to debugfs

debugfs uses the hardware for several debugfs files as such the
hardware must be initialized and available prior to its usage. The
same applies to when we free the hw structs -- free debufs file
entries prior to free'ing the hardware.

Reported-by: Vasanthakumar Thiagarajan <vasanth@atheros.com>
Signed-off-by: Luis R. Rodriguez <lrodriguez@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>