glsl: Fix ir_quadop_vector validation

glsl: Fix ir_quadop_vector validation

Some glcts tests have failed due to incorrect processing of `ir_quadop_vector` in
`ir_validation`. e.g:
`GLES31.functional.shaders.builtin_functions.integer.imulextended.int_highp_geometry`

Closes: https://gitlab.freedesktop.org/mesa/mesa/-/issues/6461
Fixes: 23cde71b ("glsl: Stop lowering ir_quadop_vector.")

Reviewed-by: Emma Anholt <emma@anholt.net>
Signed-off-by: Mykhailo Skorokhodov <mykhailo.skorokhodov@globallogic.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/16420>