Fix MISRA rule 8.4

Rule 8.4: A compatible declaration shall be visible when
an object or function with external linkage is defined

Fixed for:
	make DEBUG=1 PLAT=juno SPD=tspd CSS_USE_SCMI_SDS_DRIVER=1 all

Change-Id: Id732c8df12ef3e20903c41b7ab9a9b55341d68ac
Signed-off-by: Roberto Vargas <roberto.vargas@arm.com>

plat/arm/css/drivers/scp/css_sds.c

@@ -11,6 +11,7 @@
 #include <delay_timer.h>
 #include <platform.h>
 #include <stdint.h>
+#include "css_scp.h"
 #include "../sds/sds.h"
 
 int css_scp_boot_image_xfer(void *image, unsigned int image_size)