include: Switch to #pragma once pattern

Signed-off-by: Sylvain Munaut <tnt@246tNt.com>
diff --git a/include/osmocom/gsm/lapdm.h b/include/osmocom/gsm/lapdm.h
index 9393406..84d109d 100644
--- a/include/osmocom/gsm/lapdm.h
+++ b/include/osmocom/gsm/lapdm.h
@@ -1,5 +1,4 @@
-#ifndef _OSMOCOM_LAPDM_H
-#define _OSMOCOM_LAPDM_H
+#pragma once
 
 #include <osmocom/gsm/l1sap.h>
 #include <osmocom/gsm/lapd_core.h>
@@ -112,5 +111,3 @@
 int lapdm_phsap_dequeue_prim(struct lapdm_entity *le, struct osmo_phsap_prim *pp);
 
 /*! @} */
-
-#endif /* _OSMOCOM_LAPDM_H */