mwifiex: add support for USB8801

USB8801 is Marvell's 1x1 802.11bgn offering.
Patch adds Device IDs support and defines TX buffer size.

Signed-off-by: Yogesh Ashok Powar <yogeshp@marvell.com>
Signed-off-by: Avinash Patil <patila@marvell.com>
Signed-off-by: Nishant Sarmukadam <nishants@marvell.com>
Signed-off-by: Cathy Luo <cluo@marvell.com>
Signed-off-by: Frank Huang <frankh@marvell.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>