nir: Switch the arguments to nir_foreach_use and friends

nir: Switch the arguments to nir_foreach_use and friends

This matches the "foreach x in container" pattern found in many other
programming languages.  Generated by the following regular expression:

s/nir_foreach_use(\([^,]*\),\s*\([^,]*\))/nir_foreach_use(\2, \1)/

and similar expressions for nir_foreach_use_safe, etc.

Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>