i965/fs: add generator support for pixel interpolator query

V5: - Split into separate opcodes
    - Pass message data in src1 immediate
    - Put noperspective bit in fs_inst rather than adding any junk to
      backend_instruction

Signed-off-by: Chris Forbes <chrisf@ijw.co.nz>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
4 files changed