Make Aardvark's msi_domain_info structure into a private driver structure.
Domain info is same for every potential instatination of a controller.

Link: https://lore.kernel.org/r/20220110015018.26359-8-kabel@kernel.orgSigned-off-by: NMarek Behún <kabel@kernel.org>
Signed-off-by: NLorenzo Pieralisi <lorenzo.pieralisi@arm.com>