drm/i915: Introduce fb->min_alignment

drm/i915: Introduce fb->min_alignment

Different planes could have different alignment requirements
even for the same format/modifier. Collect the alignment
requirements across all planes capable of scanning out the
fb such that the alignment is satisfactory to all those
planes.

So far this was sort of handled by making sure intel_surf_alignment()
declares the superset of all planes' alignment requirements,
but maintaining that manually is annoying. So we're going to move
towards each plane declaring only its own requirements, and thus
we need code to generate the superset.

v2: Drop the borked per-plane vma optimization (Imre)
    Assert that the plane's declared alignment is POT (Imre)

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240612204712.31404-5-ville.syrjala@linux.intel.com
Reviewed-by: Imre Deak <imre.deak@intel.com>