wil6210: fix freeing of rx buffers in EDMA mode

After being associated with some EDMA rx traffic, upon "down" driver
doesn't free all skbs in the rx ring.
Modify wil_move_all_rx_buff_to_free_list to loop on active list of rx
buffers, unmap the physical memory and free the skb.

Change-Id: I952f0dc86a7dfce8705786ab1ee7172421cb3901
Signed-off-by: Ahmad Masri <amasri@codeaurora.org>
Signed-off-by: Maya Erez <merez@codeaurora.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Git-commit: 6470f31927b46846d957628b719dcfda05446664
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/kvalo/ath.git


Signed-off-by: Maya Erez <merez@codeaurora.org>
Signed-off-by: Lior David <liord@codeaurora.org>