mei: bus: do not start a read for disconnected clients

Avoid queuing reads and registering rx callbacks in
case the client is not connected, to prevent null
dereferencing and memory leaks.

Signed-off-by: Alexander Usyskin <alexander.usyskin@intel.com>
Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Link: https://lore.kernel.org/r/20201029095444.957924-3-tomas.winkler@intel.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>