net: ixgbe: Use new PCI_DEV_FLAGS_NO_RELAXED_ORDERING flag

The ixgbe driver use the compile check to determine if it can
send TLPs to Root Port with the Relaxed Ordering Attribute set,
this is too inconvenient, now the new flag PCI_DEV_FLAGS_NO_RELAXED_ORDERING
has been added to the kernel and we could check the bit4 in the PCIe
Device Control register to determine whether we should use the Relaxed
Ordering Attributes or not, so use this new way in the ixgbe driver.

Signed-off-by: Ding Tianhong <dingtianhong@huawei.com>
Acked-by: Emil Tantilov <emil.s.tantilov@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>