mwifiex: add support for sd8977 chipset

This patch adds support for 8977 chipset to mwifiex with SDIO
interface. Register offsets and supported feature flags are
updated. Firmware image used will be mrvl/sd8977_uapsta.bin.

Signed-off-by: Hemantkumar Suthar <shemant@marvell.com>
Signed-off-by: Rakesh Parmar <rakeshp@marvell.com>
Signed-off-by: Cathy Luo <cluo@marvell.com>
Signed-off-by: Ganapathi Bhat <gbhat@marvell.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>