mwifiex: support for creation of AP interface

1. wiphy structure is per device; hence moved it to mwifiex_adapter
mwifiex_register_cfg80211 takes mwifiex_adapter as parameter.
This function only registers wiphy with cfg80211.
2. Creation of interfaces is moved to cfg80211 add_virtual_interface
handler.
3. Create 2 interfaces by default: station and AP

Signed-off-by: Avinash Patil <patila@marvell.com>
Signed-off-by: Yogesh Ashok Powar <yogeshp@marvell.com>
Signed-off-by: Amitkumar Karwar <akarwar@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>