arm64: dts: renesas: r8a779f0: Add GPIO nodes

Add device nodes for the General Purpose Input/Output (GPIO) blocks on
the Renesas R-Car S4-8 (R8A779F0) SoC.

Note that GPIO blocks 4-7 are not added, as they can only be accessed
from the Control Domain.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/7fb68561026fa8bb5d9baf0596560c5c719a38cc.1649086225.git.geert+renesas@glider.be