drm/amd/display: STREAM_MAPPER_CONTROL register offset on DCN35

[Why]
The STREAM_MAPPER_CONTROL register offset was left uninitialized,
causing warning in the driver log at runtime

[How]
A temporary solution to add it into dcn35_create_resource_pool.

[TODO]
Remove duplication between SE_DCN35_REG_LIST_RI in dcn35_resource.h and
SE_DCN35_REG_LIST in dcn35_dio_stream_encoder.h

Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Reviewed-by: Charlene Liu <charlene.liu@amd.com>
Acked-by: Qingqing Zhuo <qingqing.zhuo@amd.com>
Signed-off-by: Artem Grishin <artem.grishin@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>