(#21874) Fix failing validation.

Validation of deprecated resource references using QualifiedName
(i.e. a lower case bare word) instead of QualifiedReference (i.e.
an upper cased bare word) should have accessed the `value` of the
instructions `left_expr`, but instead did this on the instruction
itself.

This fixes one part of the issue #21874 which gives users a better clue
how to work around the issue.
Merge branch 'master' of ssh://github.com/puppetlabs/puppet.git