dts: Add bindings for multicast hash bins and perfect filter entries

This change adds bindings for the number of multicast hash bins and perfect
filter entries supported by the Synopsys EMAC. The Synopsys EMAC core is
configurable at device creation time, and can be configured for a different
number of multicast hash bins and a different number of perfect filter
entries. The device does not provide a way to query these parameters,
therefore parameters are required. The Altera Cyclone V SOC has support for
256 multicast hash bins and 128 perfect filter entries, and is different
than what's currently provided in the stmmac driver.

Signed-off-by: Vince Bridgers <vbridgers2013@gmail.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>