i2c: rzg2l: Add I2C driver for RZ/G2L family

This driver supports the I2C module on the Renesas RZ/G2L (R9A07G044)
SoC, also known as the RIIC module.

This patch is based on both the u-boot driver in the Renesas RZ BSP
3.0.5 release [1] (commit 7fcc1fdc2534), and the Linux v6.7 driver
(commit 0dd3ee311255).

Support for deblocking the I2C bus is included as this may be needed
after triggering a reset via the Power Management IC (PMIC) over I2C
(the PMIC asserts the reset line before the SoC completes the I2C write
transaction with obvious bus locking effects). If the SDA line is
observed to be low during initialisation, we automatically attempt to
deblock.

[1]: https://github.com/renesas-rz/renesas-u-boot-cip

Signed-off-by: Paul Barker <paul.barker.ct@bp.renesas.com>
Reviewed-by: Marek Vasut <marek.vasut+renesas@mailbox.org>