nir/lower_blend: Fix nir_blend_logicop() for 8/16-bit integer formats
What does this MR do and why?
src and dst can be integer types, and doing an f2f on such types messes up with the original value. Make sure we keep the original type when {up,down}sizing the src, dst and out values.
Found while converting panvk to blend shaders.
Edited by Boris Brezillon