mac80211: Fix hwflags debugfs file format

Commit 30686bf7 ("mac80211: convert HW flags to unsigned long
bitmap") accidentally removed the newline delimiter from the hwflags
debugfs file. Fix this by adding back the newline between the HW flags.

Cc: stable@vger.kernel.org [4.2]
Signed-off-by: Mohammed Shafi Shajakhan <mohammed@qti.qualcomm.com>
[fix commit log]
Signed-off-by: Jouni Malinen <jouni@qca.qualcomm.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>