mwifiex: create separate function mwifiex_11n_dispatch_pkt()

Existing mwifiex_11n_dispatch_pkt() function is renamed as
mwifiex_11n_dispatch_pkt_until_start_win() and a new function
mwifiex_11n_dispatch_pkt() is created for a common code which
dispatches single packet based on interface type.

Signed-off-by: Amitkumar Karwar <akarwar@marvell.com>
Signed-off-by: Bing Zhao <bzhao@marvell.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>