i2c: brcmstb: use devm_platform_ioremap_resource_byname()

Convert platform_get_resource_byname(),devm_ioremap_resource() to a single
call to devm_platform_ioremap_resource_byname(), as this is exactly what
this function does.

Signed-off-by: Ye Xingchen <ye.xingchen@zte.com.cn>
Acked-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>