mwifiex: 11n specific configuration for transmit

Currently device is not able to transmit in 40MHz in spite of
enabling 40MHz support in HTCapInfo IE in assoc req, because
11n specific FW capabilities for transmission are not initialized.
This patch adds code to initilize these capabilities.

Signed-off-by: Amitkumar Karwar <akarwar@marvell.com>
Signed-off-by: Yogesh Ashok Powar <yogeshp@marvell.com>
Signed-off-by: Kiran Divekar <dkiran@marvell.com>
Signed-off-by: Bing Zhao <bzhao@marvell.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>