rename oap.h to oap_client.h

Related: OS#1592
Change-Id: I05bd65ff81b0f70f68217b2e0a9466e160bdbdec
diff --git a/openbsc/src/gprs/oap.c b/openbsc/src/gprs/oap.c
index ac2b2a4..92140c1 100644
--- a/openbsc/src/gprs/oap.c
+++ b/openbsc/src/gprs/oap.c
@@ -26,7 +26,7 @@
 #include <osmocom/crypt/auth.h>
 #include <osmocom/gsm/oap.h>
 
-#include <openbsc/oap.h>
+#include <openbsc/oap_client.h>
 #include <openbsc/debug.h>
 
 int oap_client_init(struct oap_client_config *config,