SPM: Fix build warnings

This patch fixes some build warnings

Change-Id: I749f92f7014433afede634771849242a80fc00ff
Signed-off-by: Kevin Peng <kevin.peng@arm.com>
diff --git a/secure_fw/spm/cmsis_psa/spm_ipc.c b/secure_fw/spm/cmsis_psa/spm_ipc.c
index c633256..18cb640 100644
--- a/secure_fw/spm/cmsis_psa/spm_ipc.c
+++ b/secure_fw/spm/cmsis_psa/spm_ipc.c
@@ -628,7 +628,7 @@
 
 uint32_t tfm_spm_init(void)
 {
-    uint32_t i, j;
+    uint32_t i;
     bool privileged;
     struct partition_t *partition;
     struct tfm_core_thread_t *pth, *p_ns_entry_thread = NULL;