wil6210: support max aggregation window size 64

FW can support BACK window size 64 for performance improvements.
A new FW capability is added for notifying the host on the increased
max BACK win size support.
Defining WIL_MAX_AGG_WSIZE_64 and WIL_MAX_AMPDU_SIZE_128 to be used
in this case.

Signed-off-by: Maya Erez <merez@codeaurora.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>