net: pch_gbe: Reset during probe

Using the EG20T gigabit ethernet controller on the MIPS Boston board, we
find that we have to reset the controller in order for the RGMII link to
the PHY to become functional. Without doing so we constantly time out in
pch_gbe_mdio_ready.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Tested-by: Bin Meng <bmeng.cn@gmail.com>
Signed-off-by: Daniel Schwierzeck <daniel.schwierzeck@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>