V4L/DVB (4367): Videodev: Handle class_device related errors

Add proper error checking and roll-back for failure of
class_device_create_file() in videodev.c.  Print error messages and
unroll partially created sysfs entries.
Also, failure of class_device_register() in video_register_device() is
handled correctly.  It was failing to de-allocate the minor number.  This
must be done in video_register_device(), since the caller has no way of
knowing if failure occurred before or after the class device was
registered.
Also added an error message if video_register_device() is called with
an unknown type, which should never happen.

Signed-off-by: Trent Piepho <xyzzy@speakeasy.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>