firmware: tegra: bpmp: Return directly after a failed kzalloc() in get_filename()

The kfree() function was called in one case by
the get_filename() function during error handling
even if the passed variable contained a null pointer.
This issue was detected by using the Coccinelle software.

Thus return directly after a call of the function “kzalloc” failed
at the beginning.
Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
Signed-off-by: Thierry Reding <treding@nvidia.com>

drivers/firmware/tegra/bpmp-debugfs.c

@@ -77,7 +77,7 @@ static const char *get_filename(struct tegra_bpmp *bpmp,
 
 	root_path_buf = kzalloc(root_path_buf_len, GFP_KERNEL);
 	if (!root_path_buf)
-		goto out;
+		return NULL;
 
 	root_path = dentry_path(bpmp->debugfs_mirror, root_path_buf,
 				root_path_buf_len);