mei: use uuid, me_addr tuple addressing also for flow control credits

Add uuid, me_addr addressing also for flow control credits.
The only exception in cases for single buffer clients for which
the host address in flow credits response is always 0

To in order to deal with add/remove race between fw and driver clients
addressing we need to use [uuid, me_addr] tuple to address the clients

Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>