ath6kl: Multicast filter support in wow suspend and non-suspend

This patch enables all multicast packets in non suspend mode
and enable multicast filtering in wow suspend mode. This also
fixes a bug in multicast where the driver assumed disable
multicast-all command disabled/filtered all multicast
packets, which was wrong assumption, because firmware will
apply the programmed filter.

Multicast requirements
 - Enable forward all multicast packets(no filtering) in
      non suspend mode.
 - Enable multicast filtering in wow suspend mode for both
      AP and CLIENT.

kvalo: fix a checkpatch warning and drop unrelated newline removal

Signed-off-by: Naveen Gangadharan <ngangadh@qca.qualcomm.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>