arm, am335x: siemens: enable DM/DTS support

enable basic DM/DTS support for the siemens am335x based boards.

Signed-off-by: Heiko Schocher <hs@denx.de>
diff --git a/include/configs/siemens-am33x-common.h b/include/configs/siemens-am33x-common.h
index 5969541..eab665c 100644
--- a/include/configs/siemens-am33x-common.h
+++ b/include/configs/siemens-am33x-common.h
@@ -102,8 +102,10 @@
 #define CONFIG_SYS_PTV			2	/* Divisor: 2^(PTV+1) => 8 */
 
 /* NS16550 Configuration */
+#ifdef CONFIG_SPL_BUILD
 #define CONFIG_SYS_NS16550_SERIAL
 #define CONFIG_SYS_NS16550_REG_SIZE	(-4)
+#endif
 #define CONFIG_SYS_NS16550_CLK		(48000000)
 #define CONFIG_SYS_NS16550_COM1		0x44e09000
 #define CONFIG_SYS_NS16550_COM4		0x481a6000