rlcmac: ignore PACKET_DOWNLINK_DUMMY_CONTROL_BLOCK

It's expected to receive dummy DL blocks when listening to PDCH,
so do not spam the logging with errors:

  DRLCMAC ERROR rlcmac.c:392 TS=7 FN=3035694080
    Rx Pkt DL Dummy Ctrl Block NOT SUPPORTED! ignoring

Change-Id: I6a40e2795adc71b9312d39c96b01aba9a258da42
Related: OS#5500
---
M src/rlcmac/rlcmac.c
1 file changed, 18 insertions(+), 0 deletions(-)

diff --git a/src/rlcmac/rlcmac.c b/src/rlcmac/rlcmac.c
index b090cee..3b30fb6 100644
--- a/src/rlcmac/rlcmac.c
+++ b/src/rlcmac/rlcmac.c
@@ -448,6 +448,8 @@
 	case OSMO_GPRS_RLCMAC_DL_MSGT_PACKET_UPLINK_ASSIGNMENT:
 		rc = gprs_rlcmac_handle_pkt_ul_ass(rlcmac_prim, dl_ctrl_block);
 		break;
+	case OSMO_GPRS_RLCMAC_DL_MSGT_PACKET_DOWNLINK_DUMMY_CONTROL_BLOCK:
+		break; /* Ignore dummy blocks */
 	default:
 		LOGRLCMAC(LOGL_ERROR, "TS=%u FN=%u Rx %s NOT SUPPORTED! ignoring\n",
 			  rlcmac_prim->l1ctl.pdch_data_ind.ts_nr,

