ARM: dts: am335x-bone-common: Increase MDIO reset deassert time

ARM: dts: am335x-bone-common: Increase MDIO reset deassert time

Prior to commit df16c1c51d81 ("net: phy: mdio_device: Reset device only
when necessary") MDIO reset deasserts were performed twice during boot.
Now that the second deassert is no longer performed, device probe
failures happen due to the change in timing with the following error
message:

SMSC LAN8710/LAN8720: probe of 4a101000.mdio:00 failed with error -5

Restore the original effective timing, which resolves the probe
failures.

Signed-off-by: Colin Foster <colin.foster@in-advantage.com>
Link: https://lore.kernel.org/r/20240531183817.2698445-1-colin.foster@in-advantage.com
Signed-off-by: Kevin Hilman <khilman@baylibre.com>