Bluetooth: bcm203x: Use GFP_KERNEL in workqueue

A workqueue is allowed to sleep so we can safely use GFP_KERNEL instead of
GFP_ATOMIC. This is still legacy code when the driver used timer BHs and not a
worqueue.

Signed-off-by: David Herrmann <dh.herrmann@googlemail.com>
Acked-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi>