ARM: 7192/1: OMAP: Fix build error for omap1_defconfig

Otherwise we get the following error:

In function 'omap_init_consistent_dma_size':
error: implicit declaration of function 'init_consistent_dma_size'
Signed-off-by: Tony Lindgren <tony@atomide.com>
Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

arch/arm/plat-omap/common.c

@@ -14,6 +14,7 @@
 #include <linux/kernel.h>
 #include <linux/init.h>
 #include <linux/io.h>
+#include <linux/dma-mapping.h>
 #include <linux/omapfb.h>
 
 #include <plat/common.h>