NFSv2/v3: Fix error handling in nfs_atomic_open_v23()

NFSv2/v3: Fix error handling in nfs_atomic_open_v23()

When nfs_do_create() returns an EEXIST error, it means that a regular
file could not be created. That could mean that a symlink needs to be
resolved. If that's the case, a lookup needs to be kicked off.

Reported-by: Stephen Abbene <sabbene87@gmail.com>
Link: https://bugzilla.kernel.org/show_bug.cgi?id=220710
Fixes: 7c6c5249f061 ("NFS: add atomic_open for NFSv3 to handle O_TRUNC correctly.")
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Reviewed-by: NeilBrown <neil@brown.name>
Signed-off-by: Anna Schumaker <anna.schumaker@oracle.com>