V4L/DVB (7541): em28xx: Some fixes to videobuf

It fixes a couple of minor bugs, comments out a bogus BUG_ON, sets fh->type
correctly, uses dev->width and dev->height for now, and adds a missing spinlock
init (nasty - caused a system lockup). It also adds some debug code which
probably isn't all that useful. I haven't tested this version of the patch yet,
though, so I'm not sure what you can expect if you try it.

Signed-off-by: Aidan Thornton <makosoft@googlemail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>