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.

Fixes: 7755b40d ("dt-bindings: power: add R8A77980 SYSC power domain definitions")
Fixes: 41d6d8bd ("soc: renesas: rcar-sysc: add R8A77980 support")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>