ath6kl: Configure inteface information at init time

Virtual interface information need to be configured during
init time to the target. With MAX_NUM_VIF is restricted to
1, currently only a single vif is being configured.

Signed-off-by: Vasanthakumar Thiagarajan <vthiagar@qca.qualcomm.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>