i2c: nomadik: support Mobileye EyeQ5 I2C controller

Add compatible for the integration of the same DB8500 IP block into the
Mobileye EyeQ5 platform. Two quirks are present:

 - The memory bus only supports 32-bit accesses. Avoid writeb() and
   readb() by introducing helper functions that fallback to writel()
   and readl().

 - A register must be configured for the I2C speed mode; it is located
   in a shared register region called OLB. We access that memory region
   using a syscon & regmap that gets passed as a phandle (mobileye,olb).

   A two-bit enum per controller is written into the register; that
   requires us to know the global index of the I2C controller (cell arg
   to the mobileye,olb phandle).

We add #include <linux/mfd/syscon.h> and <linux/regmap.h>.

Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Théo Lebrun <theo.lebrun@bootlin.com>
Reviewed-by: Andi Shyti <andi.shyti@kernel.org>
Signed-off-by: Andi Shyti <andi.shyti@kernel.org>