mt76: mt7615: do not mark sched_scan disabled in mt7615_scan_work

For the moment offload firmware supports just one entry in the scheduled
scan plan and so it runs till it is disabled by the userspace.
Do not mark the hw scheduled scan as disabled in mt7615_scan_work
after receiving a scan result

Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Signed-off-by: Felix Fietkau <nbd@nbd.name>