Revert "i965: Extend compute-to-mrf pass to understand blocks of MOVs"

Revert "i965: Extend compute-to-mrf pass to understand blocks of MOVs"

This reverts commit bbefb15e01e1c16af69646898918982ae00f8c92.
Fixes the 11 regressions caused in framebuffer_blit tests in
Khronos GLES3 CTS tests:

Original patch reduced the instruction count but had no performance
benefits. So, it's safe to revert it without causing any performance
regressions.

Signed-off-by: Anuj Phogat <anuj.phogat@gmail.com>
Acked-by: Kristian Høgsberg <krh@bitplanet.net>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>