media: davinci: remove vpbe support

The davinci dm3xx/dm644x platforms are gone now, and the remaining
da8xx platforms do not use the vpbe driver, so the driver can be
removed as well.

Acked-by: Lad Prabhakar <prabhakar.csengg@gmail.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>