wil6210: publish max_msdu_size to FW on BCAST ring

Set max_msdu_size in WMI_BCAST_DESC_RING_ADD_CMD to allow FW
to optimize the buffers allocation for bcast packets.

Change-Id: Id95876ddf2268d873eb1f240b0f3ac4aa0696fb4
Signed-off-by: Maya Erez <merez@codeaurora.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Git-commit: 3e7ee09d36a68a57721916899075396f7ed35a46
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/kvalo/ath.git


[merez@codeaurora.org: trivial merge conflicts]
Signed-off-by: Maya Erez <merez@codeaurora.org>