mwifiex: pass key_params pointer in mwifiex_set_encode

'cipher' and 'seq' coming from cfg80211 add_key handler will be
parsed in mwifiex_set_encode() to handle AES_CMAC cipher suite.

Signed-off-by: Ying Luo <luoy@marvell.com>
Signed-off-by: Stone Piao <piaoyun@marvell.com>
Signed-off-by: Bing Zhao <bzhao@marvell.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>