drm/i915/vma: Add helpers to check GTT view type

drm/i915/vma: Add helpers to check GTT view type

I915_GTT_VIEW_ROTATED is going away and being replaced by just
I915_GTT_VIEW_REMAPPED, so we're going to need another way to
determine if the view is rotated or not (since width/height
will need to be swapped when operating on the destination
coordinate space). Provide small helper functions to hide
such implementation details from most of the code using GTT views.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patch.msgid.link/20260407155053.32156-8-ville.syrjala@linux.intel.com
Reviewed-by: Jani Nikula <jani.nikula@intel.com>