pinctrl: renesas: rzg2l: Rename RZG2L_SINGLE_PIN_GET_PORT macro

Rename RZG2L_SINGLE_PIN_GET_PORT -> RZG2L_SINGLE_PIN_GET_PORT_OFFSET.

Also, rename port -> port_offset in rzg2l_pinctrl_pinconf_set/get for
readability.

Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Reviewed-by: Biju Das <biju.das.jz@bp.renesas.com>
Link: https://lore.kernel.org/r/20211110224622.16022-3-prabhakar.mahadev-lad.rj@bp.renesas.com


Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>