arm64: dts: zynqmp: Added GEM reset definitions

The Cadence GEM/MACB driver now utilizes the platform-level reset on the
ZynqMP platform. Add reset definitions to the ZynqMP platform device
tree to allow this to be used.

Signed-off-by: Robert Hancock <robert.hancock@calian.com>
Signed-off-by: David S. Miller <davem@davemloft.net>