drm/vmwgfx: Remove explicit transparent hugepages support

Old versions of the svga device used to export virtual vram, handling of
which was optimized on top of transparent hugepages support. Only very
old devices (OpenGL 2.1 support and earlier) used this code and at this
point performance differences are negligible.

Because the code requires very old hardware versions to run it has
been largely untested and unused for a long time.

Furthermore removal of the ttm hugepages support in:
commit 0d979509 ("drm/ttm: remove ttm_bo_vm_insert_huge()")
broke the coherency mode in vmwgfx when running with hugepages.

Fixes: 0d979509

 ("drm/ttm: remove ttm_bo_vm_insert_huge()")
Signed-off-by: Zack Rusin <zackr@vmware.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Cc: Christian König <christian.koenig@amd.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Martin Krastev <krastevm@vmware.com>
Reviewed-by: Maaz Mombasawala <mombasawalam@vmware.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20211215184147.3688785-2-zack@kde.org