drm/i915: Introduce pin_params.needs_physical

drm/i915: Introduce pin_params.needs_physical

Add a new flag pin_params.needs_physical to inform the pinning
code that the display needs a physical address and not GGTT
address.

This isn't strictly necessary as the current phys_alignment!=0
check is enough in practice. But theoretically one could have
needs_physical==true without any alignment requirements. And
having an explicit flag feels a bit less magical.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patch.msgid.link/20260416174448.28264-8-ville.syrjala@linux.intel.com
Reviewed-by: Jani Nikula <jani.nikula@intel.com>