lapdm: Update public lapdm_msg_ctx upon CCCH data ind

This allows uses accessing the updated fields such as fn from the l3_cb
when receiving a msg from CCCH, eg: "le->datalink[DL_SAPI0].mctx.fn;"

Related: OS#3626
Change-Id: Icabc3759c47b0f7cfe61f1b7a96f08f36714262e
---
M src/gsm/lapdm.c
1 file changed, 15 insertions(+), 0 deletions(-)

diff --git a/src/gsm/lapdm.c b/src/gsm/lapdm.c
index e96e218..9f795c6 100644
--- a/src/gsm/lapdm.c
+++ b/src/gsm/lapdm.c
@@ -857,6 +857,8 @@
 	case LAPDm_FMT_Bter:
 		/* fall-through */
 	case LAPDm_FMT_Bbis:
+		/* Update context so that users can read fields like fn: */
+		memcpy(&mctx.dl->mctx, &mctx, sizeof(mctx.dl->mctx));
 		/* directly pass up to layer3 */
 		msg->l3h = msg->l2h;
 		msgb_pull_to_l3(msg);

