smbd: use fsp in smb_set_file_time()

smbd: use fsp in smb_set_file_time()

Ensure we have a valid fsp whos name we pass to file_ntimes(). Remember,
file_ntimes() by default ends up calling SMB_VFS_GET_DOS_ATTRIBUTES() under the
hood in order to get/set the creation date.

As any fsp->fsp_name contains a backpointer to the fsp ie

  fsp->fsp_name->fsp == fsp

passing set_fsp->fsp_name to file_ntimes() allows replacing the path based
SMB_VFS_GET_DOS_ATTRIBUTES() with SMB_VFS_FGET_DOS_ATTRIBUTES() under the hoods.

Also use the base_fsp->fsp_name for the base name in case of setting the
timestamps on a stream.

Signed-off-by: Ralph Boehme <slow@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>