qtnfmac: remove VIF in firmware in case of error

Currently in case of error when registering network device with the
kernel, we won't properly cleanup VIF state in firmware due to DEL_VIF
command will not be send to wifi card. Make sure it does.

Signed-off-by: Igor Mitsyanko <igor.mitsyanko.os@quantenna.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>