PCI: Fix cavium quirk compile failure with PCI_ATS off

The newly added quirk_cavium_sriov_rnm_link doesn't compile if
PCI_ATS is off.  This patch adds a check for PCI_ATS.

Fixes: 21b5b8ee ("PCI: quirk fixup for cavium invalid sriov...")
Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>