On ar933x and later chips, there are separated mac/mdio resets, but
resetting the entire gmac block with register values requires both
mac_reset and mdio_reset to be asserted together.
Add support for optional mdio reset so that we can do a full reset
if needed.
This patch also replaced deprecated devm_reset_control_get for
mac reset.
To use this feature, the following is needed:
1. drop "simple-mfd" compatible to register mdio0 after gmac init
so that mdio registers aren't reset after initialization.
2. move mdio reset from mdio-bus to its parent eth node.
NOTE: This can't be applied on gmac1 with builtin switch since we
haven't add a feature to defer probe if phy connection failed.
Signed-off-by: Chuanhong Guo <gch981213@gmail.com>
cea3e9e438