mwifiex: make use of msecs_to_jiffies()

Use msecs_to_jiffies() wherever possible.

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>