pinctrl: renesas: r8a77990: Add RPC pins, groups, and functions

Add pins, groups, and functions for the SPI Multi I/O Bus Controller
(RPC-IF) to the R8A77990 PFC driver.  They are to be used when an
Octal-SPI Flash or HyperFlash is connected.

Redefine the QSPI[01] pin groups using the RPC DQ[0:7] pin data, to save
memory.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/ec9735bb3468225e04ac6cb95e11a0e237b2b9ed.1648547080.git.geert+renesas@glider.be