efi_selftest: keep devices in ExitBootServices()

When calling ExitBootServices during out unit tests we should not detach
devices as we need console output for runtime tests.

Fixes: 529441ca89 ("efi_loader: Disable devices before handing over control")
Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>

include/efi_loader.h

@@ -59,6 +59,9 @@ extern efi_handle_t efi_root;
 /* Set to EFI_SUCCESS when initialized */
 extern efi_status_t efi_obj_list_initialized;
 
+/* Flag used by the selftest to avoid detaching devices in ExitBootServices() */
+extern bool efi_st_keep_devices;
+
 /* EFI system partition */
 extern struct efi_system_partition {
 	enum if_type if_type;