riscv: Kconfig: enable SCHED_MC kconfig

RISC-V now builds the sched domain based on the simple possible map.

Enable SCHED_MC to make the building based on cpu_coregroup_mask()
which also takes care of the NUMA and cores with LLC.

Signed-off-by: Song Shuai <suagrfillet@gmail.com>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20230310110336.970985-1-suagrfillet@gmail.com


Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>