rsi: advertise ap mode support

AP mode support is advertised to cfg80211. Necessary wiphy
parameters are initialized.

Signed-off-by: Prameela Rani Garnepudi <prameela.j04cs@gmail.com>
Signed-off-by: Amitkumar Karwar <amit.karwar@redpinesignals.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>