In case of error, the function platform_device_register_simple() returns
RR_PTR() and never returns NULL. The NULL test in the return value check
should be replaced with IS_ERR().
Signed-off-by: NWei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: NScott Wood <scottwood@freescale.com>