drm/amdgpu: enable enforce_isolation sysfs node on VFs

It should be enabled on both bare metal and VFs.

Fixes: e189be9b ("drm/amdgpu: Add enforce_isolation sysfs attribute")
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: Srinivasan Shanmugam <srinivasan.shanmugam@amd.com>
Cc: Amber Lin <Amber.Lin@amd.com>
Reviewed-by: Srinivasan Shanmugam <srinivasan.shanmugam@amd.com>
(cherry picked from commit dc8847b0)