bts/osmo-bts.cfg: remove deprecated 'uplink-power-target'

Change-Id: Ida5b1357d199e222b9ebd64e833ca21e6506a36c
diff --git a/bts/osmo-bts.cfg b/bts/osmo-bts.cfg
index b7282da..a92273f 100644
--- a/bts/osmo-bts.cfg
+++ b/bts/osmo-bts.cfg
@@ -51,7 +51,6 @@
  rtp jitter-buffer 100
  paging queue-size 200
  paging lifetime 0
- uplink-power-target -75
  gsmtap-sapi rach
  gsmtap-sapi agch
  gsmtap-sapi bcch