pinctrl: renesas: r8a7792: Add bias pinconf support

Implement support for pull-up (most pins) and pull-down (EDBGREQ)
handling for the R-Car V2H SoC, using the common R-Car bias handling.

Note that the R-Car V2H Hardware User's Manual Rev. 1.00 says that
the LSI Pin Pull-Up Control Register 11 (PUPR11) controls pull-ups for
the {SCK,WS,SDATA}[01] pins.  These are assumed to be typos, as R-Car
V2H has only Serial Sound Interface channels 3 and 4.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Link: https://lore.kernel.org/r/48d2abdd63ee43ed99cb32ed4a5f4d76ba563162.1619785375.git.geert+renesas@glider.be