net: fec: add post PHY reset delay DT property

Some PHY require to wait for a bit after the reset GPIO has been
toggled. This adds support for the DT property `phy-reset-post-delay`
which gives the delay in milliseconds to wait after reset.

If the DT property is not given, no delay is observed. Post reset delay
greater than 1000ms are invalid.

Signed-off-by: Quentin Schulz <quentin.schulz@free-electrons.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Acked-by: Fugang Duan <fugang.duan@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Documentation/devicetree/bindings/net/fsl-fec.txt

@@ -15,6 +15,10 @@ Optional properties:
 - phy-reset-active-high : If present then the reset sequence using the GPIO
   specified in the "phy-reset-gpios" property is reversed (H=reset state,
   L=operation state).
+- phy-reset-post-delay : Post reset delay in milliseconds. If present then
+  a delay of phy-reset-post-delay milliseconds will be observed after the
+  phy-reset-gpios has been toggled. Can be omitted thus no delay is
+  observed. Delay is in range of 1ms to 1000ms. Other delays are invalid.
 - phy-supply : regulator that powers the Ethernet PHY.
 - phy-handle : phandle to the PHY device connected to this device.
 - fixed-link : Assume a fixed link. See fixed-link.txt in the same directory.