pinctrl: renesas: rzg2l: Add support for selecting power source for {WDT,AWO,ISO}

pinctrl: renesas: rzg2l: Add support for selecting power source for {WDT,AWO,ISO}

The RZ/G3L SoC has support for setting power source that are not
controlled by the following voltage control registers:
  - SD_CH{0,1,2}_POC, XSPI_POC, ETH{0,1}_POC, I3C_SET.POC

Add support for selecting voltages using OTHER_POC register for
setting I/O domain voltage for WDT, ISO and AWO by extending
rzg2l_caps_to_pwr_reg() with a mask output parameter so that callers
callers can identify which bit(s) within OTHER_POC correspond to the
requested domain. Update rzg2l_get_power_source() to extract the
relevant bit field via field_get() when reading OTHER_POC, and update
rzg2l_set_power_source() to perform a read-modify-write under the
spinlock when writing to OTHER_POC, since multiple domains share the
same register.

Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://patch.msgid.link/20260430093422.74812-4-biju.das.jz@bp.renesas.com
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>