drm/amd/display: dc_get_vmid_use_vector() crashes when get called

[Why]
int i can go out of boundary which will cause crash

[How]
Fixed the maximum value of i to avoid i going out of boundary

Signed-off-by: Peikang Zhang <peikang.zhang@amd.com>
Reviewed-by: Jun Lei <Jun.Lei@amd.com>
Acked-by: Bhawanpreet Lakha <Bhawanpreet.Lakha@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>