r8152: sync ocp base

There are some chances that the actual base of hardware is different
from the value recorded by driver, so we have to reset the variable
of ocp_base to sync it.

Set ocp_base to -1. Then, it would be updated and the new base would be
set to the hardware next time.

Signed-off-by: Hayes Wang <hayeswang@realtek.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>