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: NYufeng Mo <moyufeng@huawei.com>
Signed-off-by: NHuazhong Tan <tanhuazhong@huawei.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>