mei: cancel stall timers in mei_reset

Unset init_clients_timer and amthif_stall_timers
in mei_reset in order to cancel timer ticking and hence
avoid recursive reset calls.

Cc:  <stable@vger.kernel.org> # 3.9+
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>