[Why] struct mpc has no instance identifier, unlike other DC hardware blocks. Debug and tracing helpers need one to identify the block. [How] Add an inst member to struct mpc and initialize it to 0 in every dcnXX_mpc_construct(), since there is one MPC instance per ASIC. Reviewed-by: Jun Lei <jun.lei@amd.com> Signed-off-by: Tony Cheng <Tony.Cheng@amd.com> Signed-off-by: Chenyu Chen <chen-yu.chen@amd.com> Tested-by: Daniel Wheeler <daniel.wheeler@amd.com> Signed-off-by: Alex Deucher <alexander.deucher@amd.com>