efi_loader: Fix warning in raw/cols query

The code to determine rows / cols on the screen could potentially run
into a case where it doesn't know how big the screen is. In that case,
assume 80x25.

Signed-off-by: Alexander Graf <agraf@suse.de>
diff --git a/lib/efi_loader/efi_console.c b/lib/efi_loader/efi_console.c
index 0bfc24d..ce66c93 100644
--- a/lib/efi_loader/efi_console.c
+++ b/lib/efi_loader/efi_console.c
@@ -223,7 +223,7 @@
 static void query_console_size(void)
 {
 	const char *stdout_name = env_get("stdout");
-	int rows, cols;
+	int rows = 25, cols = 80;
 
 	if (stdout_name && !strcmp(stdout_name, "vidconsole") &&
 	    IS_ENABLED(CONFIG_DM_VIDEO)) {