soc: renesas: r8a77980-sysc: Correct A3VIP[012] power domain hierarchy
The R-Car Gen3 HardWare Manual Errata for Rev. 0.80 (Feb 28, 2018)
renamed the A3VIP power domain on R-Car V3H to A3VIP0, and clarified the
power domain hierarchy for the A3VIP[012] power domains.
As the definition for the A3VIP0 domain is not yet used from DT, it can
just be renamed.