i965/fs: Add support for nir_op_[iu]642d
i965/fs: Add support for nir_op_[iu]642d

Reviewed-by: Lionel Landwerlin <9463032a5b99ffad10f36631678a833369a311b5@intel.com>
Reviewed-by: Samuel Iglesias Gonsálvez <b753b212f30aed827c3eea2e437609dc37310153@igalia.com>

metora/MesaGLSLCompiler,metora/MesaGLSLCompiler,metora/MesaGLSLCompiler