fs: exfat: Implement trivial 'rename' support

Implement exfat_fs_rename() to rename or move files. This is used
by the 'mv' generic FS interface command. The rename implementation
for other filesystems was added recently and was not part of exfat
porting layer due to merge issue, which made 'mv' command crash,
fix this by adding the missing implementation.

Fixes: b86a651b64 ("fs: exfat: Add U-Boot porting layer")
Signed-off-by: Marek Vasut <marex@denx.de>

fs/exfat/io.c

@@ -1013,6 +1013,11 @@ exit:
 	return err;
 }
 
+int exfat_fs_rename(const char *old_path, const char *new_path)
+{
+	return exfat_rename(&ctxt.ef, old_path, new_path);
+}
+
 void exfat_fs_close(void)
 {
 	exfat_unmount(&ctxt.ef);

fs/fs.c

@@ -401,6 +401,7 @@ static struct fstype_info fstypes[] = {
 		.ln = fs_ln_unsupported,
 		.unlink = exfat_fs_unlink,
 		.mkdir = exfat_fs_mkdir,
+		.rename = exfat_fs_rename,
 	},
 #endif
 	{