mt76: mt7615: remove a stray if statement

This if statement was supposed to be deleted, but it wasn't.  It means
that we sometimes don't set the sensitivity correctly.

Fixes: 2cad515e ("mt76: mt7615: add missing settings for simultaneous dual-band support")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Felix Fietkau <nbd@nbd.name>