BS Power Control Loop: Increase attenuation if RxQual is better than upper threshold
BS Power Control Loop: Increase attenuation if RxQual is better than upper threshold

If RxQual is considered good enough, attenuation can be increased in
order to lower overall cross-channel noise among different MS.

Change-Id: Ie97898980acd152de15f6b4b619d492048855ef4

osmocom/osmo-bts,osmocom/osmo-bts,osmocom/osmo-bts