Test: Remove unused header file

Remove unused header file of tfm_assert.h from main_ns.c.

Change-Id: I202e3cfec727ae816a21a646812d9119635b546b
Signed-off-by: Shawn Shan <Shawn.Shan@arm.com>
diff --git a/app/main_ns.c b/app/main_ns.c
index 53a4f47..7ad6680 100644
--- a/app/main_ns.c
+++ b/app/main_ns.c
@@ -24,7 +24,6 @@
 #include "tfm_multi_core_api.h"
 #include "tfm_ns_mailbox.h"
 #endif
-#include "log/tfm_assert.h"
 #include "tfm_log.h"
 #include "uart_stdout.h"
 #include "region.h"