MLK-14915 mx6ul_arm2/mx6ull_arm2: Fix ENET PHY reset issue

MLK-14915 mx6ul_arm2/mx6ull_arm2: Fix ENET PHY reset issue

There are two pins used for ENET PHY reset, need to assert them before init the PHY.
Current DM driver does not have such operation, need board level codes to handle.
This patch moves the PHY reset operation into setup_fec, which is common for DM driver
and non-DM driver.

Signed-off-by: Ye Li <ye.li@nxp.com>