mwifiex: save adapter pointer in wiphy_priv

Since wiphy structure is per adapter we would save adapter,
instead of mwifiex private pointer, in wiphy_priv.
Also move country_info from mwifiex_private to mwifiex_adapter
as making it part of mwifiex_adapter looks logical.

Signed-off-by: Avinash Patil <patila@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>