pinctrl: renesas: r8a779f0: Add INTC-EX pins, groups, and function

Add pins, groups, and function for the Interrupt Controller for External
Devices (INTC-EX) on the Renesas R-Car S4-8 (R8A779F0) SoC.

Based on a larger patch in the BSP by LUU HOAI.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Link: https://lore.kernel.org/r/dc6e25da42ac4bd19ca31b5b32b43a10a0e1aa7e.1645457792.git.geert+renesas@glider.be