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/bts.h b/src/bts.h
index 1498ced..0928f8d 100644
--- a/src/bts.h
+++ b/src/bts.h
@@ -155,6 +155,7 @@
 	uint8_t cs3;
 	uint8_t cs4;
 	uint8_t initial_cs_dl, initial_cs_ul;
+	uint8_t initial_mcs_dl, initial_mcs_ul;
 	uint8_t max_cs_dl, max_cs_ul;
 	uint8_t max_mcs_dl, max_mcs_ul;
 	uint8_t force_cs;	/* 0=use from BTS 1=use from VTY */