drm/i915/skl: Fix DMC load on Skylake J0 and K0

The driver does not load firmware for unknown steppings, so these new
steppings must be added to the list.

Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1454023163-25469-1-git-send-email-mathew.j.martineau@linux.intel.com