mei: squash single_recv_buf into one bit in client properties

single_recv_buf member of struct mei_client_properties has a boolean
value and can be represented in on bit, to free other 7 bits
for another usage.

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>