nir: use nir_shader_instructions_pass in nir_lower_frexp

Changes:
- nir_metadata_preserve(..., nir_metadata_all) is called when pass doesn't
  make progress

Signed-off-by: Marcin Ślusarz <marcin.slusarz@intel.com>
Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>
175 jobs for !13272 with wip/frexp-cleanup in 15 minutes and 54 seconds (queued for 54 minutes and 28 seconds)
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