[PATCH] V4L: Fix read() bugs in bttv driver

Fix read() bugs in bttv driver.

Signed-off-by: Nickolay V. Shmyrev <nshmyrev@yandex.ru>
Signed-off-by: Michael H. Schimek <mschimek@gmx.at>
Signed-off-by: Mauro Carvalho Chehab <mchehab@brturbo.com.br>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>