erofs: Fallback to normal access if DAX is not supported on extra device

If using multiple devices, we should check if the extra device support
DAX instead of checking the primary device when deciding if to use DAX
to access a file.

If an extra device does not support DAX we should fallback to normal
access otherwise the data on that device will be inaccessible.

Signed-off-by: Yuezhang Mo <Yuezhang.Mo@sony.com>
Reviewed-by: Friendy Su <friendy.su@sony.com>
Reviewed-by: Jacky Cao <jacky.cao@sony.com>
Reviewed-by: Daniel Palmer <daniel.palmer@sony.com>
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Reviewed-by: Hongbo Li <lihongbo22@huawei.com>
Link: https://lore.kernel.org/r/20250804082030.3667257-2-Yuezhang.Mo@sony.com


Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>