[KERNAL] remove support for non-FX VERA versions

[mooinglemur]

We have had the deprecation warning at boot for old VERAs for the last 9 months, it's probably okay to remove the check at this point.

After this change, this is what would likely happen on old VERAs:

• Unversioned = display will probably go blank once it reaches BASIC and the cursor starts blinking
• 0.1.1 - display will be offset to the right as it inadvertently sets HSTART to a high value, you can only see a small region.

Both situations can be recovered from via an AUTOBOOT.X16 that loads a flash tool.