nir/validate: Allow 32-bit boolean load/store intrinsics

nir/validate: Allow 32-bit boolean load/store intrinsics

With UBOs and SSBOs we have boolean types but they're actually 32-bit
values.  Make the validator a little less strict so that we can do a
32-bit load/store on boolean types.  We're about to add a lowering pass
called gl_nir_lower_buffers which will lower boolean load/store
operations to 32-bit and insert i2b and b2i instructions to convert
to/from 1-bit booleans.  We want that to be legal.

Reviewed-by: Kristian H. Kristensen <hoegsberg@chromium.org>
Reviewed-by: Caio Marcelo de Oliveira Filho <caio.oliveira@intel.com>