smb: client: fix regression with native SMB symlinks

In the Linux kernel, the following vulnerability has been resolved:

smb: client: fix regression with native SMB symlinks

Some users and customers reported that their backup/copy tools started

to fail when the directory being copied contained symlink targets that

the client couldn't parse - even when those symlinks weren't followed.

Fix this by allowing lstat(2) and readlink(2) to succeed even when the

client can't resolve the symlink target, restoring old behavior.