FogBugz #559720: remove dummy client from service layer

Dummy client is not real service layer provider. It was created and used
to validate the communications among service provider, service layer
driver and secure monitor SW while we initially developed service layer
driver.

Dummy client is no longer need, and it should be removed from service
layer, since we have real service providers now (FPGA manager, RSU).

Signed-off-by: Richard Gong <richard.gong@intel.com>