iwlwifi: fix debug print in iwl_sta_calc_ht_flags

We missed passing an argument to the
debug print. Fix it.

Cc: stable@kernel.org
Signed-off-by: Meenakshi Venkataraman <meenakshi.venkataraman@intel.com>
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>