spl, common, serial: build SPL without serial support

This patch enables building SPL without
CONFIG_SPL_SERIAL_SUPPORT support.

Signed-off-by: Heiko Schocher <hs@denx.de>
[trini: Ensure we build arch/arm/imx-common on mx28]
Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/arch/arm/mach-at91/spl_at91.c b/arch/arm/mach-at91/spl_at91.c
index a79a9dc..b19f95b 100644
--- a/arch/arm/mach-at91/spl_at91.c
+++ b/arch/arm/mach-at91/spl_at91.c
@@ -123,9 +123,12 @@
 	at91_periph_clk_enable(ATMEL_ID_PIOB);
 	at91_periph_clk_enable(ATMEL_ID_PIOC);
 #endif
+
+#if defined(CONFIG_SPL_SERIAL_SUPPORT)
 	/* init console */
 	at91_seriald_hw_init();
 	preloader_console_init();
+#endif
 
 	mem_init();