pch_gbe: export a method to set the receive match address

The code in phc_gbe_main will need to call this method in order to set the
station address register according to the receive time stamping filter.

[ RC - Rebased Takahiro's changes and wrote a commit message
  explaining the changes. ]

Signed-off-by: Takahiro Shimizu <tshimizu818@gmail.com>
Signed-off-by: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>