pinctrl: renesas: rzg2l: Add support for different DS values on different groups

RZ/G3S supports different drive strength values for different power
sources and pin groups (A, B, C).  On each group there could be up to 4
drive strength values per power source.  Available power sources are
1v8, 2v5, 3v3.  Drive strength values are more fine tuned than what was
previously available on the driver thus the necessity of having
micro-amp support.  As drive strength and power source values are linked
together the hardware setup for these was moved at the end of
rzg2l_pinctrl_pinconf_set() to ensure proper validation of the new
values.

The drive strength values are expected to be initialized though the
SoC-specific hardware configuration data structure.

Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/20230929053915.1530607-19-claudiu.beznea@bp.renesas.com
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>

Author: claudiubeznea