iommu/ipmmu-vmsa: Hook up r8a779(70|95) DT matching code

Support the r8a77970 (R-Car V3M) and r8a77995 (R-Car D3) IPMMUs by sharing
feature flags with r8a7795 (R-Car H3) and r8a7796 (R-Car M3-W). Also update
IOMMU_OF_DECLARE to hook up the compat strings.

Based on work for the r8a7796 by Magnus Damm

[rebased on v4.17]
Signed-off-by: Jacopo Mondi <jacopo+renesas@jmondi.org>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Joerg Roedel <jroedel@suse.de>