rsi: Add support to filter rx frames

Filtering rx frames after connection in station mode avoids the
overhead of processing un-necessary frames. Hence rx filter frame
is added which can be configured to device at suitable times.

Signed-off-by: Prameela Rani Garnepudi <prameela.j04cs@gmail.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>