Add the register PNP_IO4, which will be used by IT5570E in CB:48894.
Change-Id: Ic820295247323f546d4c48ed17cfa4eab3dc5e92
Signed-off-by: Michael Niewöhner <foss@mniewoehner.de>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/48924
Reviewed-by: Felix Singer <felixsinger@posteo.net>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>