i2c: ocores: Use devm_request_and_ioremap()

Replacing the devm_request_mem_region() and devm_ioremap_nocache() calls
by a single call to devm_request_and_ioremap() simplifies the code.

Signed-off-by: Thierry Reding <thierry.reding@avionic-design.de>
Acked-by: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Wolfram Sang <w.sang@pengutronix.de>