gallium: Add format modifier aux plane query

Rather than hard-code a list of all the format modifiers supported by any gallium driver in the dri state tracker, add a screen proc that queries the number of auxiliary planes required for a given modifier+format pair.

Since the only format modifier that requires auxiliary planes currently is the iris driver's I915_FORMAT_MOD_Y_TILED_CCS, provide a generic implementation of this screen proc as a utility function, and use that in every driver besides the iris driver, which requires a trivial customization on top of it.

Signed-off-by: James Jones jajones@nvidia.com