i2c: omap: use devm_platform_ioremap_resource()

Use a new API devm_platform_ioremap_resource() to simplify code.

Signed-off-by: chenqiwu <chenqiwu@xiaomi.com>
Tested-by: Luca Ceresoli <luca@lucaceresoli.net>
Reviewed-by: Luca Ceresoli <luca@lucaceresoli.net>
Reviewed-by: Vignesh Raghavendra <vigneshr@ti.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>