staging: bcm2835-camera: Restore return behavior of ctrl_set_bitrate()

The commit 52c4dfce ("Staging: vc04_services: Cleanup in
ctrl_set_bitrate()") changed the return behavior of ctrl_set_bitrate().
We cannot do this because of a bug in the firmware, which breaks probing
of bcm2835-camera:

    bcm2835-v4l2: mmal_init: failed to set all camera controls: -3
    Cleanup: Destroy video encoder
    Cleanup: Destroy image encoder
    Cleanup: Destroy video render
    Cleanup: Destroy camera
    bcm2835-v4l2: bcm2835_mmal_probe: mmal init failed: -3
    bcm2835-camera: probe of bcm2835-camera failed with error -3

So restore the old behavior, add an explaining comment and a debug message
to verify that the bug has been fixed in firmware.

Fixes: 52c4dfce

 ("Staging: vc04_services: Cleanup in ctrl_set_bitrate()")
Signed-off-by: Stefan Wahren <wahrenst@gmx.net>
Cc: stable <stable@vger.kernel.org>
Acked-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>