gplug: fixed build error as a result of code cleanup patch

Signed-off-by: Prafulla Wadaskar <prafulla@marvell.com>

board/Marvell/gplugd/gplugd.c

@@ -30,6 +30,7 @@
 
 #include <common.h>
 #include <mvmfp.h>
+#include <asm/arch/cpu.h>
 #include <asm/arch/mfp.h>
 #include <asm/arch/armada100.h>
 #include <asm/gpio.h>