Fix remaining refs to pkg.compare

Pull request #7636 fixed a regression caused by refs to a removed
execution function 'pkg.compare'. This function was moved to salt.utils
and made a common interface so that version comparison could be done
elsewhere in the salt codebase, and these refs were missed when doing
the cleanup.
Merge pull request #7642 from terminalmage/pkg-compare-regression-fix

Fix remaining refs to pkg.compare