Alignment trick doesn't work properly for ppgtt gens - kernel is able
to keep previous offset and doesn't call unbind/bind. With softpin
on ppgtt we're able to enforce rebind and benchmark should behave
correctly on such gens.

To avoid inaccurate results kernel CONFIG_PROVE_LOCKING should be set
to N, otherwise kernel can call unbind/bind for same offset more than
one (backoff is not visible from userspace).

v2: rename to gem_allows_obj_alignment()

Signed-off-by: Zbigniew Kempczyński <zbigniew.kempczynski@intel.com>
Cc: Petri Latvala <petri.latvala@intel.com>
Cc: Ashutosh Dixit <ashutosh.dixit@intel.com>
Reviewed-by: Ashutosh Dixit <ashutosh.dixit@intel.com>