dm: Use dm_scan_fdt_dev() directly where possible

Quite a few places have a bind() method which just calls dm_scan_fdt_dev().
We may as well call dm_scan_fdt_dev() directly. Update the code to do this.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/test/dm/spi.c b/test/dm/spi.c
index 2e27da7..5733096 100644
--- a/test/dm/spi.c
+++ b/test/dm/spi.c
@@ -30,8 +30,8 @@
 						       false, &bus));
 
 	/*
-	 * spi_post_bind() will bind devices to chip selects. Check this then
-	 * remove the emulation and the slave device.
+	 * The post_bind() method will bind devices to chip selects. Check
+	 * this then remove the emulation and the slave device.
 	 */
 	ut_asserteq(0, uclass_get_device_by_seq(UCLASS_SPI, busnum, &bus));
 	ut_assertok(spi_cs_info(bus, cs, &info));