iwlwifi: fix TX power antenna access

commit a5fdde28b4f5fb756032e7ad2c6fcdcffde20958 upstream.

Since my commit
  iwlwifi: use valid TX/RX antenna from hw_params
the config values are pure overrides, not the
real values for all hardware. Therefore, the
EEPROM TX power reading code checks the wrong
values, it should check the hw_params values.

Reviewed-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>