efi_loader: fix StartImage bootservice

The calling convention for the entry point of an EFI image
is always 'asmlinkage'.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Signed-off-by: Alexander Graf <agraf@suse.de>
diff --git a/lib/efi_loader/efi_boottime.c b/lib/efi_loader/efi_boottime.c
index ff11d02..029dc09 100644
--- a/lib/efi_loader/efi_boottime.c
+++ b/lib/efi_loader/efi_boottime.c
@@ -1533,7 +1533,8 @@
 					   unsigned long *exit_data_size,
 					   s16 **exit_data)
 {
-	ulong (*entry)(efi_handle_t image_handle, struct efi_system_table *st);
+	asmlinkage ulong (*entry)(efi_handle_t image_handle,
+				  struct efi_system_table *st);
 	struct efi_loaded_image *info = image_handle;
 	efi_status_t ret;