ath9k_hw: Read and configure quick drop for AR9003

Read and configure quick drop feild from AR9003 eeprom
inorder to help with strong signal. This patch also removes
obsolate parameters ob, db_stage2, db_stage_3, db_stage4
from the eeprom templates.

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