spd: add static qualifier to locally used functions and data

These are used locally in a file.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
diff --git a/services/spd/trusty/trusty.c b/services/spd/trusty/trusty.c
index 97f202c..f5501c9 100644
--- a/services/spd/trusty/trusty.c
+++ b/services/spd/trusty/trusty.c
@@ -53,7 +53,7 @@
 	uint64_t	r7;
 };
 
-struct trusty_cpu_ctx trusty_cpu_ctx[PLATFORM_CORE_COUNT];
+static struct trusty_cpu_ctx trusty_cpu_ctx[PLATFORM_CORE_COUNT];
 
 struct args trusty_init_context_stack(void **sp, void *new_stack);
 struct args trusty_context_switch_helper(void **sp, void *smc_params);