ns16550: unify serial_omap

Unify serial_omap, and use the generic binding.

Signed-off-by: Thomas Chou <thomas@wytron.com.tw>
Reviewed-by: Tom Rini <trini@konsulko.com>
Acked-by: Simon Glass <sjg@chromium.org>
diff --git a/board/overo/overo.c b/board/overo/overo.c
index 20cbec2..a38b959 100644
--- a/board/overo/overo.c
+++ b/board/overo/overo.c
@@ -74,7 +74,7 @@
 };
 
 U_BOOT_DEVICE(overo_uart) = {
-	"serial_omap",
+	"ns16550_serial",
 	&overo_serial
 };