iwlegacy: remove enum iw_calib and related code

Remove the enum il_calib. It defined one identifier: IL_CALIB_MAX.
Remove the function il4965_calib_free_results. It was doing nothing
because IL_CALIB_MAX is zero. Next, remove calib_results from the
il_priv structure and also remove the associated return
type/struct il_calib_result.

Signed-off-by: Greg Dietsche <Gregory.Dietsche@cuw.edu>
Signed-off-by: John W. Linville <linville@tuxdriver.com>