ARM: davinci: remove support for cam_enc_4xx

This has not been converted to Generic Board, so should be removed.
(See doc/README.generic-board for details.)

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: Heiko Schocher <hs@denx.de>
Acked-by: Marek Vasut <marex@denx.de>