staging: erofs: drop __GFP_NOFAIL for managed inode

For historical reasons, __GFP_NOFAIL was set for managed inode.
It's no need using that since EROFS can handle it properly.

Signed-off-by: Gao Xiang <gaoxiang25@huawei.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Link: https://lore.kernel.org/r/20190731155752.210602-13-gaoxiang25@huawei.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>