r8152: fix the issue about U1/U2

- Disable U1/U2 during initialization.
- Disable lpm when linking is on, and enable it when linking is off.
- Disable U1/U2 when enabling runtime suspend.

It is possible to let hw stop working, if the U1/U2 request occurs
during some situations. The patch is used to avoid it.

Signed-off-by: Hayes Wang <hayeswang@realtek.com>
Signed-off-by: David S. Miller <davem@davemloft.net>