drm/i915/dmc: add support for package_header with version 2

The only meaninful change is that it supports up to 32 fw_info entries
rather than the previous max=20.

Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
Reviewed-by: Anusha Srivatsa <anusha.srivatsa@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190607091230.1489-4-lucas.demarchi@intel.com