ARM: keystone2: Fix serial port init

With CONFIG_DM_SERIAL is enabled NS16550_init() cannot be
called directly. Driver probe should be taking care of this.
So call this function only when DM_SERIAL is not enabled.
Signed-off-by: NLokesh Vutla <lokeshvutla@ti.com>

arch/arm/mach-keystone/init.c

@@ -122,8 +122,10 @@ int arch_cpu_init(void)
 	 * UART register PWREMU_MGMT is initialized. Linux UART
 	 * driver doesn't handle this.
 	 */
+#ifndef CONFIG_DM_SERIAL
 	NS16550_init((NS16550_t)(CONFIG_SYS_NS16550_COM2),
 		     CONFIG_SYS_NS16550_CLK / 16 / CONFIG_BAUDRATE);
+#endif
 
 	return 0;
 }