ERS: reset RasterInfo.RegistrationCellX/Y if setting a new geotransform on an updated .ers file (based on patch by wilsonwaters, #5493)

git-svn-id: https://svn.osgeo.org/gdal/trunk@27418 f0d54148-0727-0410-94bb-9a71ac55c965
Merge branch 'trunk' into trunk_travis_macosx