drm/amdgpu/vi: silence an uninitialized variable warning

Smatch complains that we need to initialized "*cap" otherwise it can
lead to an uninitialized variable bug in the caller.  This seems like a
reasonable warning and it doesn't hurt to silence it at least.

drivers/gpu/drm/amd/amdgpu/vi.c:767 vi_asic_reset_method() error: uninitialized symbol 'baco_reset'.

Fixes: 425db255 ("drm/amdgpu: expose BACO interfaces to upper level from PP")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>