OMAP3 Fix compiler warning for v7_flush_dcache_all

On build of omap3 targets in MAKEALL, the *.ERR files have

cpu.c: In function 'cleanup_before_linux':
cpu.c:64: warning: implicit declaration of function 'v7_flush_dcache_all'
cpu.c:64: warning: implicit declaration of function 'get_device_type

The functions v7_flush_dcache_all and get_device_type are declared
in include/asm-arm/arch-omap3/sys_proto.h, so use this file to
declare the functions.

Signed-off-by: Tom Rix <Tom.Rix@windriver.com>

cpu/arm_cortexa8/cpu.c

@@ -35,6 +35,9 @@
 #include <command.h>
 #include <asm/system.h>
 #include <asm/cache.h>
+#ifndef CONFIG_L2_OFF
+#include <asm/arch/sys_proto.h>
+#endif
 
 static void cache_flush(void);