Merge branch 'dwmac-mediatek'

Biao Huang says:

====================
complete dwmac-mediatek driver and fix flow control issue

Changes in v2:
        patch#1: there is no extra action in mediatek_dwmac_remove, remove it

v1:
This series mainly complete dwmac-mediatek driver:
        1. add power on/off operations for dwmac-mediatek.
        2. disable rx watchdog to reduce rx path reponding time.
        3. change the default value of tx-frames from 25 to 1, so
           ptp4l will test pass by default.

and also fix the issue that flow control won't be disabled any more
once being enabled.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>