fix(spmd): remove spmd_handle_spmc_message

The function `spmd_handle_spmc_message` was added into SPMD for
potential cases of SPMC sending a message (through SMC conduit)
to the SPMD. There is no longer a use case for this scenario.

Instead, if such a message is received by SPMD, return FFA_ERROR.

Signed-off-by: Kathleen Capella <kathleen.capella@arm.com>
Change-Id: I74eda4cc0edf99c83a96d10981cf6d9e727207f8
1 file changed