cifs: map NT_STATUS_SHARING_VIOLATION to EBUSY instead of ETXTBSY

NT_SHARING_VIOLATION errors are mapped to ETXTBSY which is unexpected
for operations such as unlink where we can hit these errors.

The patch maps the error NT_SHARING_VIOLATION to EBUSY instead. The
patch also replaces all instances of ETXTBSY in
cifs_rename_pending_delete() with EBUSY.

Signed-off-by: Sachin Prabhu <sprabhu@redhat.com>
Reviewed-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>