intel/blorp: Fix a couple asserts around image copy rectangles

intel/blorp: Fix a couple asserts around image copy rectangles

With dealing with rectangles in compressed images, you can have a width or
height that isn't a multiple of the corresponding compression block
dimension but only if that edge of your rectangle is on the edge of the
image.  When we call convert_to_single_slice, it creates an 2-D image and a
set of tile offsets into that image.  When detecting the right-edge and
bottom-edge cases, we weren't including the tile offsets so the assert
would misfire.  This caused crashes in a few UE4 demos

Signed-off-by: Jason Ekstrand <jason@jlekstrand.net>
Reported-by: "Eero Tamminen" <eero.t.tamminen@intel.com>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=98431
Cc: "13.0" <mesa-stable@lists.freedesktop.org>
Tested-by: "Eero Tamminen" <eero.t.tamminen@intel.com>
Reviewed-by: Iago Toral Quiroga <itoral@igalia.com>