soc/intel/common/cse: Declare g_cse statically

Change-Id: I91b6ce3b52d987e2fc0f79e550fda2891502bfe8
Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/33023
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Furquan Shaikh <furquan@google.com>

src/soc/intel/common/block/cse/cse.c

@@ -69,7 +69,7 @@
 #define MEI_HDR_CSE_ADDR	(((1 << 8) - 1) << MEI_HDR_CSE_ADDR_START)
 
 
-struct cse_device {
+static struct cse_device {
 	uintptr_t sec_bar;
 } g_cse CAR_GLOBAL;