DM: serial: ti_omap3_common: Don't define serial unless !DM_SERIAL

The serial port was being manually configured during SPL build,
however in preparation to allow DM in SPL, this needs to change
to be based on whether or not DM_SERIAL is enabled because, soon
the assumption that SPL means no DM may not be accurate.
Signed-off-by: NAdam Ford <aford173@gmail.com>
Reviewed-by: NSimon Glass <sjg@chromium.org>

include/configs/ti_omap3_common.h

@@ -27,12 +27,10 @@
 /* NS16550 Configuration */
 #define V_NS16550_CLK			48000000	/* 48MHz (APLL96/2) */
 #define CONFIG_SYS_NS16550_CLK		V_NS16550_CLK
-#if defined(CONFIG_SPL_BUILD)
-#define CONFIG_SYS_NS16550_SERIAL
 #if !defined(CONFIG_DM_SERIAL)
+#define CONFIG_SYS_NS16550_SERIAL
 #define CONFIG_SYS_NS16550_REG_SIZE	(-4)
 #endif /* !CONFIG_DM_SERIAL */
-#endif /* CONFIG_SPL_BUILD */
 #define CONFIG_SYS_BAUDRATE_TABLE	{4800, 9600, 19200, 38400, 57600, \
 					115200}