mwifiex: cleanup ioctl.h

Some structures and macros in ioctl.h are redundant or no longer
used.

Signed-off-by: Bing Zhao <bzhao@marvell.com>
Signed-off-by: Yogesh Ashok Powar <yogeshp@marvell.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>