drm/i915: Follow a new->old platform check order in intel_fb_stride_alignment

Follow the usual new->old order in intel_fb_stride_alignment() platform
check ladder.

Cc: Juha-Pekka Heikkila <juhapekka.heikkila@gmail.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Juha-Pekka Heikkila <juhapekka.heikkila@gmail.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210906182715.3915100-5-imre.deak@intel.com