i2c: rcar: (cosmetic) remove superfluous parenthesis

A recent patch added even more superfluous parenthesis to those, which
already were there. Remove them again.

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski+renesas@gmail.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>