arm: mxs: Prevent serial console init when in very early SPL boot code

When DM_SERIAL is enabled on mxs (i.e. imx28) platform, the console
early initialization must be postponed until the driver model is
correctly setup.

Signed-off-by: Lukasz Majewski <lukma@denx.de>
diff --git a/arch/arm/cpu/arm926ejs/mxs/spl_boot.c b/arch/arm/cpu/arm926ejs/mxs/spl_boot.c
index 763d79e..5598c55 100644
--- a/arch/arm/cpu/arm926ejs/mxs/spl_boot.c
+++ b/arch/arm/cpu/arm926ejs/mxs/spl_boot.c
@@ -128,8 +128,10 @@
 
 	mxs_iomux_setup_multiple_pads(iomux_setup, iomux_size);
 
-	mxs_spl_console_init();
-	debug("SPL: Serial Console Initialised\n");
+	if (!CONFIG_IS_ENABLED(DM_SERIAL)) {
+		mxs_spl_console_init();
+		debug("SPL: Serial Console Initialised\n");
+	}
 
 	mxs_power_init();