drm/msm: Fix range size vs end confusion

The fourth param is size, rather than range_end.

Note that we could increase the address space size if we had a way to
prevent buffers from spanning a 4G split, mostly just to avoid fw bugs
with 64b math.

Fixes: 84c31ee1

 ("drm/msm/a6xx: Add support for per-instance pagetables")
Signed-off-by: Rob Clark <robdclark@chromium.org>
Link: https://lore.kernel.org/r/20220407202836.1211268-1-robdclark@gmail.com
Signed-off-by: Rob Clark <robdclark@chromium.org>