drm/xe: Return 2MB page size for compact 64k PTEs

Compact 64k PTEs are only intended to be used within a single VMA which
covers the entire 2MB range of the compact 64k PTEs. Add
XE_VMA_PTE_COMPACT VMA flag to indicate compact 64k PTEs are used and
update xe_vma_max_pte_size to return at least 2MB if set.

v2: Include missing changes

Fixes: 8f33b4f0 ("drm/xe: Avoid doing rebinds")
Fixes: c47794bd

 ("drm/xe: Set max pte size when skipping rebinds")
Reported-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Closes: https://gitlab.freedesktop.org/drm/xe/kernel/-/issues/758
Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240219211942.3633795-4-matthew.brost@intel.com