include: Switch to #pragma once pattern

Signed-off-by: Sylvain Munaut <tnt@246tNt.com>
diff --git a/include/osmocom/gsm/l1sap.h b/include/osmocom/gsm/l1sap.h
index c21abe5..9f3fe98 100644
--- a/include/osmocom/gsm/l1sap.h
+++ b/include/osmocom/gsm/l1sap.h
@@ -1,5 +1,4 @@
-#ifndef _OSMOCOM_L1SAP_H
-#define _OSMOCOM_L1SAP_H
+#pragma once
 
 #include <osmocom/core/prim.h>
 
@@ -121,5 +120,3 @@
 		struct mph_info_param info;
 	} u;			/*!< \brief request-specific data */
 };
-
-#endif /* _OSMOCOM_L1SAP_H */