intel/compiler: initial compiler changes for xe2/lnl register size change; adds reg_unit()

Merged Jordan Justen requested to merge jljusten/mesa:xe2-reg-unit into main

The register size is doubling for Xe2/lnl, so these patches introduce a reg_unit() function to adjust sizes in various places. Additional MR's will add more related changes as other areas of the compiler are updated for Xe2.

Includes patches from @currojerez, @shadeslayer, @idr, @cmarcelo and @jljusten.

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