PF supports all debugfs command, but VF only supports part of
debugfs command. So VF should not show unsupported help information.

This patch adds a check for PF and PF to show the supportable help
information.
Signed-off-by: Yufeng Mo <moyufeng@huawei.com>
Signed-off-by: Huazhong Tan <tanhuazhong@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>