pinctrl: renesas: rzg2l: Add PFC_OEN support for RZ/G3E SoC

pinctrl: renesas: rzg2l: Add PFC_OEN support for RZ/G3E SoC

Add support for configuring the PFC_OEN register on the RZ/G3E SoC to
enable output-enable control for specific pins. On this SoC, certain
pins such as TXC_TXCLK need to support switching between input and
output modes depending on the PHY interface mode (e.g., MII vs RGMII).
This functionality maps to the 'output-enable' property in the device
tree and requires explicit control via the PFC_OEN register.

This change updates the r9a09g047_variable_pin_cfg array to mark PB1, PE1,
PL0, PL1, PL2, and PL4 with the PIN_CFG_OEN flag to indicate output-enable
support. A new helper, rzg3e_pin_to_oen_bit(), is introduced to map these
pin names to their respective OEN bit positions, and the corresponding
callbacks are wired into the RZ/G3E SoC configuration using the generic
rzg2l_read_oen() and rzg2l_write_oen() accessors. Additionally, the GPIO
configuration for the PB, PE, and PL ports is updated to use the variable
port pack macro, enabling per-pin configuration necessary for OEN handling.

Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/20250806195555.1372317-7-prabhakar.mahadev-lad.rj@bp.renesas.com
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>