i2c: cadence: Add RISCV architecture support

Add RISCV support to Cadence I2C Kconfig which is used in platform
such as the StarFive JH8100.

Signed-off-by: Eng Lee Teh <englee.teh@starfivetech.com>
Signed-off-by: Ji Sheng Teoh <jisheng.teoh@starfivetech.com>
Signed-off-by: Andi Shyti <andi.shyti@kernel.org>