xen: arm: Enable 1:1 workaround by default

xen: arm: Enable 1:1 workaround by default

I was just about to send out patches adding the 1:1 workaround to vexpress
(the foundation model is a vexpress platfrom with DMA) and sunxi.

That would have meant that all platforms now implement the quirk. Instead lets
just make it the default and remove the quirk.

In the future this will likely be set based on the presence absence of an
IOMMU, perhaps with additional overrides by the platform.

This results in some dead code in domain_build for dealing with the non-1:1
case. This is deliberate and is left in anticipation of IOMMU support in 4.5.

PLATFORM_QUIRK_GIC_64K_STRIDE is renumbered as a side effect of this change.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Acked-by: Julien Grall <julien.grall@linaro.org>