mwl8k: le32_to_cpu cast to restricted

It fixes couple of sparse check
>#make C=1 CF=-D__CHECK_ENDIAN__ drivers/net/wireless/mwl8k.o
>drivers/net/wireless/mwl8k.c:3104:19: warning: cast to restricted __le32
>drivers/net/wireless/mwl8k.c:3108:18: warning: cast to restricted __le32

Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Nishant Sarmukadam <nishants@marvell.com>
Signed-off-by: Yogesh Ashok Powar <yogeshp@marvell.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>