mt76: add back the SUPPORTS_REORDERING_BUFFER flag

It was accidentally dropped while adding multiple wiphy support
Fixes fast-rx support and avoids handling reordering in both mac80211
and the driver

Cc: stable@vger.kernel.org
Fixes: c89d3625

 ("mt76: add function for allocating an extra wiphy")
Signed-off-by: Felix Fietkau <nbd@nbd.name>