iwlagn: remove MACDUMP debug

This is only used for TX debugging where there
already is more debugging and tracing is more
useful anyway, so remove it.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>