dtb: amd: Fix GICv2 hypervisor and virtual interface sizes

This patch fixes incorrect sizes of the GICv2 device tree node.
This has triggered error message when booting Xen hypervisor.

Signed-off-by: Brijesh Singh <brijeshkumar.singh@amd.com>
Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Signed-off-by: Olof Johansson <olof@lixom.net>