intel/brw: nir: Fix handling of cmat_signed_mask
For integer types, the signedness is determined by flags on the muladd instruction. The types of the sources play no role. Previously we were using the signedness of the type and ignoring the mask.
Adjust the types passed to the dpas_intel
intrinsic to match.
Fixes various dEQP-VK.compute.*.cooperative_matrix.khr_*.matrixmuladd_cross.* tests on different Intel platforms. Some platforms had failing tests, and some platforms failed EU validation before the tests could fail.
Fixes: 6b14da33 ("intel/fs: nir: Add nir_intrinsic_dpas_intel")