drm/i915: Add struct to hold IP version

Adding a structure to standardize access to IP versioning as future
platforms will have this information populated at runtime.

The constant platform display version is not using this new struct but
the runtime variant will definitely use it.

Cc: Radhakrishna Sripada <radhakrishna.sripada@intel.com>
Cc: Matt Atwood <matthew.s.atwood@intel.com>
Signed-off-by: José Roberto de Souza <jose.souza@intel.com>
Reviewed-by: Caz Yokoyama <caz.yokoyama@intel.com>
Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20211020002353.193893-1-jose.souza@intel.com