dm: keystone: serial: Add driver model support

Add driver model support for keystone serial driver.

Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>
Acked-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/serial/Makefile b/drivers/serial/Makefile
index 869ea7b..1818c7c 100644
--- a/drivers/serial/Makefile
+++ b/drivers/serial/Makefile
@@ -25,6 +25,7 @@
 obj-$(CONFIG_LPC32XX_HSUART) += lpc32xx_hsuart.o
 obj-$(CONFIG_MCFUART) += mcfuart.o
 obj-$(CONFIG_OPENCORES_YANU) += opencores_yanu.o
+obj-$(CONFIG_KEYSTONE_SERIAL) += serial_keystone.o
 obj-$(CONFIG_SYS_NS16550) += ns16550.o
 obj-$(CONFIG_S5P) += serial_s5p.o
 obj-$(CONFIG_IMX_SERIAL) += serial_imx.o