Huge page-table entries for TTM

In order to reduce CPU usage [1] and in theory TLB misses this patchset enables
huge- and giant page-table entries for TTM and TTM-enabled graphics drivers.
Signed-off-by: Dave Airlie <airlied@redhat.com>
From: Thomas Hellstrom (VMware) <thomas_os@shipmail.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20200325073102.6129-1-thomas_os@shipmail.org