pinctrl: renesas: rzg2l: Reorganize variable configuration macro

pinctrl: renesas: rzg2l: Reorganize variable configuration macro

The `PIN_CFG_VARIABLE` macro did not indicate the capabilities of a pin
but served as a flag indicating that the pins of a port have different
capabilities.

To better reflect its purpose, move the `PIN_CFG_VARIABLE` macro beside
`RZG2L_SINGLE_PIN` and rename it to `RZG2L_VARIABLE_CFG`. Additionally,
introduce new macros for packing variable port configurations:
  - `RZG2L_GPIO_PORT_PACK_VARIABLE(n, a)`: Combines `RZG2L_VARIABLE_CFG`
    with `RZG2L_GPIO_PORT_PACK` to handle variable pin configurations
    for a packed port.
  - `RZG2L_GPIO_PORT_SPARSE_PACK_VARIABLE(m, a)`: Combines
    `RZG2L_VARIABLE_CFG` with `RZG2L_GPIO_PORT_SPARSE_PACK` to handle
    variable pin configurations for a sparse port.

Due to the above change the configuration macros have been reorganized
as follows:
- Shift the bit positions of `PIN_CFG_NOGPIO_INT`, `PIN_CFG_NOD`,
  `PIN_CFG_SMT`, `PIN_CFG_ELC`, and `PIN_CFG_IOLH_RZV2H` down by one
  to accommodate the removal of `PIN_CFG_VARIABLE`.

Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Tested-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
Link: https://lore.kernel.org/r/20240618174831.415583-5-prabhakar.mahadev-lad.rj@bp.renesas.com
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>