ath9k: common-spectral: don't depend from ATH9K_DEBUGFS

we can have here two variants. Add
ATH9K_CMN_DEBUGFS y if ATH9K_CMN_DEBUGFS || ATH9K_HTC_DEBUGFS
wich will add more configurations and testcases. Or remove ATH9K_HTC_DEBUGFS
which need more time to be done.

So, make common-spectral ignore ATH9K_DEBUGFS option for now.

Signed-off-by: Oleksij Rempel <linux@rempel-privat.de>
Signed-off-by: John W. Linville <linville@tuxdriver.com>