Bluetooth: handle priority change within quote

The quote is calculated based on the first buffer in the queue so if the
priority changes to something lower than the priority of the first skb
the quote needs to be recalculated.

Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
Acked-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi>