mei: amthif: use rx_wait queue also for amthif client

Switch using cl->rx_wait wait queue also for amthif, there is nothing
special about amthif in that matter in Rx flow.
The cl->wait is reserved for hbm flows and asynchronous events

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