nir/algebraic: Use "uint" instead of "unsigned" for uint types

nir/algebraic: Use "uint" instead of "unsigned" for uint types

This is consistent with the rename done for the rest of NIR.  Currently,
"bool" is the only type specifier used in nir_opt_algebraic.py so this is
really a no-op.

Reviewed-by: Samuel Iglesias Gonsálvez <siglesias@igalia.com>
Reviewed-by: Iago Toral Quiroga <itoral@igalia.com>