mwl8k: update to ap firmware API version 2

Firmware APIv2 adds the following enhancements:

-- capabilities are reported by the firmware
-- API supports up to 8 dedicated AMPDU streams
-- optional packet timestamping and expiration can be enabled.
   Specifically, packets that are queued in firmware for longer
   than 500ms will be dropped if this option is used.

Based on work by "Nishant Sarmukadam" <nishants@marvell.com>

Signed-off-by: Brian Cavagnolo <brian@cozybit.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>