intel/blorp: Support blits and clears on surfaces with offsets

For certain EGLImage cases, we represent a single slice or LOD of an
image with a byte offset to a tile and X/Y intratile offsets to the
given slice.  Most of i965 is fine with this but it breaks blorp.  This
is a terrible way to represent slices of a surface in EGL and we should
stop some day but that's a very scary and thorny path.  This gets blorp
to start working with those surfaces and fixes some dEQP EGL test bugs.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=106629


Cc: mesa-stable@lists.freedesktop.org
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
(cherry picked from commit ae514ca6)