l1sap: fix: enable UL SACCH repetition if RxQual threshold is 0
l1sap: fix: enable UL SACCH repetition if RxQual threshold is 0

It is expected that setting RxQual threshold to 0 would make the
L1SAP logic enable repetition for both Uplink SACCH and Downlink
FACCH unconditionally.  However, this was only valid for the
later.  Let's add the missing check and make it consistent.

Change-Id: Ia44a134e7f28ea990798d1b79c87b644504c0876
Related: SYS#5114

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