pinctrl: sh-pfc: r8a7778: Use new macros for non-GPIO pins

Update the R-Car M1A pin control driver to use the new macros for
describing pins without GPIO functionality.  This replaces the use of
physical pin numbers on the R-Car M1A SoC (in 25x25 FCBGA package) by
symbolic enum values, referring to signal names.

Note that the user-visible names of these pins are still based on pin
numbers instead of signal names, to preserve DT backwards compatibility.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>