In case of error, the function ioremap() returns NULL
not ERR_PTR(). The IS_ERR() test in the return value
check should be replaced with NULL test.
Signed-off-by: NWei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>