coding: Always initialize bit counters in gsm0503_pdtch_egprs_decode().

Previsouly there were a lot of valid code paths which returned from the function
before setting bit counters which led to bogus BER output in osmo-bts-trx logs
when those code paths were hit.

Change-Id: I4722cae3794ccbb12001113c991d9cf345a52a96
diff --git a/src/coding/gsm0503_coding.c b/src/coding/gsm0503_coding.c
index 088b8bb..7385d23 100644
--- a/src/coding/gsm0503_coding.c
+++ b/src/coding/gsm0503_coding.c
@@ -938,6 +938,11 @@
 	struct egprs_cps cps;
 	union gprs_rlc_ul_hdr_egprs *hdr;
 
+	if (n_errors)
+		*n_errors = 0;
+	if (n_bits_total)
+		*n_bits_total = 0;
+
 	if ((nbits != GSM0503_GPRS_BURSTS_NBITS) &&
 		(nbits != GSM0503_EGPRS_BURSTS_NBITS)) {
 		/* Invalid EGPRS bit length */