drm/i915: Reject set-tiling-ioctl with stride==0 and a tiling mode

drm/i915: Reject set-tiling-ioctl with stride==0 and a tiling mode

In commit 957870f93412 ("drm/i915: Split out i915_gem_object_set_tiling()"),
I swapped an alignment check for IS_ALIGNED and in the process removed
the less-than check. That check turns out to be important as it was the
only rejection for stride == 0. Tvrtko did spot it, but I was
overconfident in the IS_ALIGNED() conversion.

Fixes: 957870f93412 ("drm/i915: Split out i915_gem_object_set_tiling()")
Testcase: igt/gem_tiling_max_stride
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170203105652.27819-1-chris@chris-wilson.co.uk
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
(cherry picked from commit 52da22e7aba155be238faff4f6e97b2eb9de64f3)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>