ath9k: make few eeprom and calib items static

This fixes the sparse complaints:

drivers/net/wireless/ath9k/eeprom.c:1407:5: warning: symbol
'ath9k_hw_4k_get_spur_channel' was not declared. Should it be static?
drivers/net/wireless/ath9k/eeprom.c:1436:19: warning: symbol
'eep_4k_ops' was not declared. Should it be static?
drivers/net/wireless/ath9k/eeprom.c:2808:5: warning: symbol
'ath9k_hw_def_get_spur_channel' was not declared. Should it be static?
drivers/net/wireless/ath9k/eeprom.c:2837:19: warning: symbol
'eep_def_ops' was not declared. Should it be static?
  CC [M]  drivers/net/wireless/ath9k/eeprom.o
  CHECK   drivers/net/wireless/ath9k/mac.c
  CC [M]  drivers/net/wireless/ath9k/mac.o
  CHECK   drivers/net/wireless/ath9k/calib.c
drivers/net/wireless/ath9k/calib.c:883:6: warning: symbol 'ar9285_clc'
was not declared. Should it be static?

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