If dmam_alloc_attrs() fails, it returns NULL pointer and never
return ERR_PTR(), so repleace IS_ERR() with IS_ERR_OR_NULL()
and if it's NULL, returns -ENOMEM.

Fixes: 9ba26f5c ("ARM: sa1100/assabet: move dmabounce hack to ohci driver")
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Link: https://lore.kernel.org/r/20221125064120.2842452-1-yangyingliang@huawei.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>