drm/amdgpu: Move mca debug mode decision to ras

Refactor code such that ras block decides the default mca debug mode,
and not swsmu block.

By default mca debug mode is set to false.

v2: squash in uninitialized value fix (Alex)

Signed-off-by: Lijo Lazar <lijo.lazar@amd.com>
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>