vfio: platform: Make printed error messages more consistent

  - Capitalize the first word of error messages,
  - Unwrap statements that fit on a single line,
  - Use "VFIO" instead of "vfio" as the error message prefix.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Acked-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>