ath9k: ar9003_eeprom.c:3618 fix variable name typo

   drivers/net/wireless/ath/ath9k/ar9003_eeprom.c: In function 'ar9003_hw_ant_ctrl_apply':
>> drivers/net/wireless/ath/ath9k/ar9003_eeprom.c:3618: warning: 'regval' is used uninitialized in this function

It seems obvious that 'regval' should have been 'value'...

Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>