kernel: dt_driver: Add driver probing also for external device tree use

When external device tree is configured for use OP-TEE's drivers should be
loaded based on its definitions. Add support to probe drivers also with
external device tree.

This allows same system device tree to be used to define devices for
bootloader, OP-TEE and OS.

In any case if embedded device tree is defined this will take precedense.

Signed-off-by: Vesa Jääskeläinen <vesa.jaaskelainen@vaisala.com>

core/kernel/dt_driver.c

@@ -677,12 +677,10 @@ static TEE_Result probe_dt_drivers_early(void)
 	TEE_Result res = TEE_ERROR_GENERIC;
 	const void *fdt = NULL;
 
-	if (!IS_ENABLED(CFG_EMBED_DTB))
+	fdt = get_dt();
+	if (!fdt)
 		return TEE_SUCCESS;
 
-	fdt = get_embedded_dt();
-	assert(fdt);
-
 	parse_node(fdt, fdt_path_offset(fdt, "/"));
 
 	res = process_probe_list(fdt);
@@ -700,12 +698,10 @@ static TEE_Result probe_dt_drivers(void)
 	TEE_Result res = TEE_ERROR_GENERIC;
 	const void *fdt = NULL;
 
-	if (!IS_ENABLED(CFG_EMBED_DTB))
+	fdt = get_dt();
+	if (!fdt)
 		return TEE_SUCCESS;
 
-	fdt = get_embedded_dt();
-	assert(fdt);
-
 	res = process_probe_list(fdt);
 	if (res || !TAILQ_EMPTY(&dt_driver_failed_list)) {
 		EMSG("Probe sequence result: %#"PRIx32, res);
@@ -726,13 +722,12 @@ static TEE_Result release_probe_lists(void)
 	struct dt_driver_probe *next = NULL;
 	struct dt_driver_provider *prov = NULL;
 	struct dt_driver_provider *next_prov = NULL;
-	const void * __maybe_unused fdt = NULL;
+	const void *fdt = NULL;
 
-	if (!IS_ENABLED(CFG_EMBED_DTB))
+	fdt = get_dt();
+	if (!fdt)
 		return TEE_SUCCESS;
 
-	fdt = get_embedded_dt();
-
 	assert(fdt && TAILQ_EMPTY(&dt_driver_probe_list));
 
 	TAILQ_FOREACH_SAFE(elt, &dt_driver_ready_list, link, next)