MT#61856 call_interfaces: block silence media, iteration bug

For-cycle expects the `sink_ml` for setting the `call_media`
at the upper level of the cycle, but instead the `monologue`
is used, which is supposed to be used in the nested for-cycle.

Looks like a copy-paste typo. Major fix.

Change-Id: I225a51fde7fa8d10bac832ce5fc5444ee544e882

daemon/call_interfaces.c

@@ -1744,7 +1744,7 @@ static const char *call_block_silence_media(ng_command_ctx_t *ctx, bool on_off,
 			/* now check if any sink ml media is susbcribed to any of monologue medias */
 			for (int i = 0; i < sink_ml->medias->len; i++)
 			{
-				struct call_media * sink_md = monologue->medias->pdata[i];
+				struct call_media * sink_md = sink_ml->medias->pdata[i];
 				if (!sink_md)
 					continue;
 				for (int j = 0; j < monologue->medias->len; j++)