edge: Get EGPRS multislot class

The EGPRS MS class ist contained in the MS_RA_capability information.
Its presence indicates, that the MS is able (and willing) to use
EGPRS.

This commit implements basic support for retrieving, storing, and
showing it in the VTY. The information is stored in the MS object.

Sponsored-by: On-Waves ehf
diff --git a/src/decoding.h b/src/decoding.h
index 31be032..03dad47 100644
--- a/src/decoding.h
+++ b/src/decoding.h
@@ -28,6 +28,7 @@
 	static int tlli_from_ul_data(const uint8_t *data, uint8_t len,
 					uint32_t *tlli);
 	static uint8_t get_ms_class_by_capability(MS_Radio_Access_capability_t *cap);
+	static uint8_t get_egprs_ms_class_by_capability(MS_Radio_Access_capability_t *cap);
 
 	static void extract_rbb(const uint8_t *rbb, char *extracted_rbb);
 };