Get rid of class GprsCodingScheme

We have same kind of object splitted into two layers, in coding_scheme
and gprs_coding_scheme. Let's merge them together and get rid of the
class, which is not really useful because it's only a set of functions
operating on one enum value.

This change also fixes gcc 10.1.0 error about memseting a complex type
in rlc.h init().

Change-Id: Ie9ce2144ba9e8dbba9704d4e0000a2929e3e41df
diff --git a/src/encoding.h b/src/encoding.h
index 2365f07..5bdd4ef 100644
--- a/src/encoding.h
+++ b/src/encoding.h
@@ -21,9 +21,10 @@
 #pragma once
 
 #include <stdint.h>
-#include <gprs_coding_scheme.h>
+
 extern "C" {
 #include <osmocom/gsm/l1sap.h>
+#include "coding_scheme.h"
 #include "gsm_rlcmac.h"
 }
 
@@ -99,7 +100,7 @@
 	};
 
 	static AppendResult rlc_data_to_dl_append(
-		struct gprs_rlc_data_block_info *rdbi, GprsCodingScheme cs,
+		struct gprs_rlc_data_block_info *rdbi, enum CodingScheme cs,
 		gprs_llc *llc, int *offset, int *num_chunks,
 		uint8_t *data, bool is_final, int *count_payload);
 };