edge: Add initial_mcs_dl and initial_mcs_ul config values

Provide the initial MCS values for EGPRS data blocks. They are set
to 1 (MCS-1) for each direction and there is no support to change
these configuration values yet (the automatic adaption still works,
so there is probably no need to set these values).

Sponsored-by: On-Waves ehf
diff --git a/src/pcu_main.cpp b/src/pcu_main.cpp
index 4156c4b..39de055 100644
--- a/src/pcu_main.cpp
+++ b/src/pcu_main.cpp
@@ -163,6 +163,7 @@
 	bts = bts_main_data();
 	bts->fc_interval = 1;
 	bts->initial_cs_dl = bts->initial_cs_ul = 1;
+	bts->initial_mcs_dl = bts->initial_mcs_ul = 1;
 	bts->cs1 = 1;
 	bts->t3142 = 20;
 	bts->t3169 = 5;