ARM: omap3logic: Specify DM serial driver as omap_serial

With the new omap_serial driver, this patch uses this instead
from the former ns16550_serial driver.  Even though the
omap_serial driver is essentially the same.

Signed-off-by: Adam Ford <aford173@gmail.com>
diff --git a/board/logicpd/omap3som/omap3logic.c b/board/logicpd/omap3som/omap3logic.c
index 2f63e76..cd6dd72 100644
--- a/board/logicpd/omap3som/omap3logic.c
+++ b/board/logicpd/omap3som/omap3logic.c
@@ -50,7 +50,7 @@
 };
 
 U_BOOT_DEVICE(omap3logic_uart) = {
-	"ns16550_serial",
+	"omap_serial",
 	&omap3logic_serial
 };