PCI: Add a REBAR size quirk for Sapphire RX 5600 XT Pulse

RX 5600 XT Pulse advertises support for BAR 0 being 256MB, 512MB,
or 1GB, but it also supports 2GB, 4GB, and 8GB. Add a rebar
size quirk so that the BAR 0 is big enough to cover complete VARM.

Signed-off-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Nirmoy Das <nirmoy.das@amd.com>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Link: https://patchwork.kernel.org/project/dri-devel/patch/20210107175017.15893-5-nirmoy.das@amd.com