ath6kl: Fix AP mode operation after interface down/up

When operating AP interface is brough down the mode is reset to
STA. This STA will be reconfigured into AP mode when the interface
is brought up again. This sequence will be successful only when
change_virtual_intf() returns with no error, but there is a
check in this callback which does the type change only when
that interface is active. This callback does nothing more
than saving the new interface type to vif and wdev, so the
sanity check for interface state and wmi state is not necessary.
This makes the AP interface functional again after interface down/up.

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