JPEG2000: fix regression when reading a JPEG2000 file with GCPs (or geotransform), but no valid projection, from a GeoTIFF box (linked to #5249, trunk only)

git-svn-id: https://svn.osgeo.org/gdal/trunk@26640 f0d54148-0727-0410-94bb-9a71ac55c965