smc: Make it possible to include gsm0411_smc.h as first header file
The code embeds the timer so one needs to include the header file.
diff --git a/include/osmocom/gsm/gsm0411_smc.h b/include/osmocom/gsm/gsm0411_smc.h
index e1508a2..2140db4 100644
--- a/include/osmocom/gsm/gsm0411_smc.h
+++ b/include/osmocom/gsm/gsm0411_smc.h
@@ -1,6 +1,7 @@
#ifndef _GSM0411_SMC_H
#define _GSM0411_SMC_H
+#include <osmocom/core/timer.h>
#include <osmocom/gsm/protocol/gsm_04_11.h>
#define GSM411_MMSMS_EST_REQ 0x310