arm64: dts: renesas: r8a779g0: Add GPIO nodes

Add device nodes for the General Purpose Input/Output (GPIO) blocks on
the Renesas R-Car V4H (R8A779G0) SoC.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/81176a5e12a5828cdcdd4b107d0b2e5970232c31.1662715538.git.geert+renesas@glider.be