i2c: nomadik: fetch i2c-transfer-timeout-us property from devicetree

Allow overriding the default timeout value (200ms) from devicetree,
using the generic i2c-transfer-timeout-us property.

The i2c_adapter->timeout field is an unaccurate jiffies amount;
i2c-nomadik uses hrtimers for timeouts below one jiffy.

Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Andi Shyti <andi.shyti@kernel.org>
Signed-off-by: Théo Lebrun <theo.lebrun@bootlin.com>
Signed-off-by: Andi Shyti <andi.shyti@kernel.org>