staging: bcm2835-camera: Update TODO

Remove the TODO item to remove manual cache flushing from bulk_receive.
This was previously done in this commit:

commit 7e8dbea4 ("staging: bcm2835-camera: Remove explicit cache
flush operations")

Signed-off-by: Aymen Qader <qader.aymen@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>