coding: move eB adjustement to appropriate place

As a leftover from code move from OsmoBTS we have eB adjustement outside
of eB check in gsm0503_tch_burst_map() which is rightfully noted by
Coverity. Let's fix this by moving the adjustement under the
corresponding if.

Change-Id: I385cd6ffea4d13ef911910fc87c92b73809888a2
Fixes: CID57691
diff --git a/src/coding/gsm0503_mapping.c b/src/coding/gsm0503_mapping.c
index 1e37fce..f7532eb 100644
--- a/src/coding/gsm0503_mapping.c
+++ b/src/coding/gsm0503_mapping.c
@@ -92,13 +92,8 @@
 			eB[i] = iB[i];
 		for (i = 58 - odd; i < 114; i += 2)
 			eB[i + 2] = iB[i];
-	}
-
-	if (h) {
-		if (!odd)
-			eB[58] = *h;
-		else
-			eB[57] = *h;
+		if (h)
+			eB[odd ? 57 : 58] = *h;
 	}
 }