mwifiex: Small cleanup for handling virtual interface type changes

Handle the obvious invalid virtual interface type changes with a general
check instead of looking at the individual change.

For type changes from P2P_CLIENT to P2P_GO and the other way round, this
changes the behavior slightly: We now still do nothing, but return
-EOPNOTSUPP instead of 0. Now that behavior was incorrect before and
still is, because type changes between these two types are actually
possible and supported, which we'll fix in a following commit.

Signed-off-by: Jonas Dreßler <verdre@v0yd.nl>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20210914195909.36035-2-verdre@v0yd.nl