staging: media: remove davinci vpfe_capture driver

This driver was for the davinci dm644x and dm3xx platforms that are
now removed from the kernel, so there are no more users.

Acked-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Acked-by: Lad Prabhakar <prabhakar.csengg@gmail.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>