Revert "Fix for Epson V550"

This reverts commit 9e023e8ac06008d961731f7f1a5883562e1d397e.
Fix for Epson V550

On the Epson V550 scanner, the maximum resolution is a function of the
area to be scanned. To make the higher resolutions available, in
datasource.cs, the area to be scanned needs to be set before the
resolution is set.