iwlagn: semaphore and calib cleanup

All agn devices use the same eeprom semaphore and calib version routines.
Delete the indirection and move the semaphore routines to where they are
used and make static.

Signed-off-by: Don Fry <donald.h.fry@intel.com>
Signed-off-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>