drm/via: Fix style issues in via_3d_reg header

- Fix comments using wrong style
- Drop repeated word

This fixes all checkpatch complains and makes the file a little
bit easier to read - as the eye is not distracted by the style
violations.

Suggested-by: Thomas Zimmermann <tzimmermann@suse.de>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Acked-by: Thomas Zimmermann <tzimmermann@suse.de>
Cc: Kevin Brace <kevinbrace@bracecomputerlab.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220713170202.1798216-14-sam@ravnborg.org