[BUGFIX] Upgrade wizard fails if no deprecated properties are found

Upgrade Wizard "Deprecated RTE properties in Page TS Config" fails
when no deprecated properties are used at all.

Make it a success, but keep the information message.

Change-Id: I0e0919cc02536a12d84da3d37cea64afe3af12e3
Resolves: #28593
Releases: 4.6
Reviewed-on: http://review.typo3.org/3908
Reviewed-by: Stanislas Rolland
Tested-by: Stanislas Rolland