drm/i915: Remove intel_range_t and intel_p2_t typedefs

Those are only used for defining struct intel_limit, so use anonymous
structs instead.

Signed-off-by: Ander Conselvan de Oliveira <ander.conselvan.de.oliveira@intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1462353119-9738-2-git-send-email-ander.conselvan.de.oliveira@intel.com