i965/fs: Hook up SIMD lowering to handle texturing opcodes of unsupported width.

i965/fs: Hook up SIMD lowering to handle texturing opcodes of unsupported width.

This should match the set of cases in which we currently call fail()
or no16() from the emit_texture_*() methods and the ones in which
emit_texture_gen4() enables the SIMD16 workaround.

Hint for reviewers: It's not a big deal if I happen to have missed
some case here, it will just lead to an assertion failure down the
road which is easily fixable, however being stricter than necessary
won't cause any visible breakage, it would just decrease performance
silently due to the unnecessary message splitting, so feel free to
double-check that all cases listed here already cause a SIMD8/16
fall-back with the current texturing code -- You may want to skip over
the Gen5-6 cases though if you don't have pencil and paper at hand.

Reviewed-by: Jason Ekstrand <jason.ekstrand@intel.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>