efi: selftest: Make record static

record is only referenced in efi_selftest_exitbootservices.c

Signed-off-by: Bin Meng <bmeng@tinylab.org>
diff --git a/lib/efi_selftest/efi_selftest_exitbootservices.c b/lib/efi_selftest/efi_selftest_exitbootservices.c
index 11b43fd..b090ce7 100644
--- a/lib/efi_selftest/efi_selftest_exitbootservices.c
+++ b/lib/efi_selftest/efi_selftest_exitbootservices.c
@@ -27,7 +27,7 @@
 
 static struct efi_boot_services *boottime;
 static struct efi_event *efi_st_event_notify;
-struct notification_record record;
+static struct notification_record record;
 
 struct notification_context context_before = {
 	.record = &record,