mwl8k: report rate and other information for received frames

When receiving a frame, report the antenna info, long/short preamble
status, 20/40 MHz flag, long/short guard interval status, MCS/legacy
rate status, and MCS/legacy rate index to the stack.

Signed-off-by: Lennert Buytenhek <buytenh@marvell.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>