qtnfmac: add interface combination check for repeater mode

Firmware supports only STA as primary interface in repeater mode.
Since the only meaningful usage of AP + STA interface combination
is repeater, reject such combination with AP as primary interface.

Signed-off-by: Dmitry Lebed <dlebed@quantenna.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>