i965: Rework the modifier info map

i965: Rework the modifier info map

This commit splits the mapping in half.  The modifier_infos table now
only contains the modifier and the since_gen field.  The tiling bits
have been moved into a table in tiling_to_modifier as that's the only
place it was ever used.  The modifier_is_supported function now takes a
devinfo and does the since_gen check.

Reviewed-by: Daniel Stone <daniels@collabora.com>