ath9k_hw: Remove read-only registers from AR9003 intervals

This patch removes read only registers that cause invalid
address access and also updates index for measurement filter
calibration window size.

Signed-off-by: Rajkumar Manoharan <rmanohar@qca.qualcomm.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>