arm: exynos: Include missing CPU header in soc.c

samsung_get_base_swreset() is called in soc.c, but corresponding header
with its prototype is not included. Fix this to avoid possible build
errors.

Signed-off-by: Sam Protsenko <semen.protsenko@linaro.org>
Signed-off-by: Minkyu Kang <mk7.kang@samsung.com>

arch/arm/mach-exynos/soc.c

@@ -9,6 +9,7 @@
 #include <asm/cache.h>
 #include <asm/io.h>
 #include <asm/system.h>
+#include <asm/arch/cpu.h>
 
 #ifdef CONFIG_TARGET_ESPRESSO7420
 /*