PCI: Abstract LBMS seen check into pcie_lbms_seen()

JIRA: https://issues.redhat.com/browse/RHEL-81906
Upstream Status: 3491f509666865412ad344cd4dde9f3c5a52326e

commit 3491f509666865412ad344cd4dde9f3c5a52326e
Author: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Date:   Fri Oct 18 17:47:51 2024 +0300

    PCI: Abstract LBMS seen check into pcie_lbms_seen()

    The Target Speed quirk in pcie_failed_link_retrain() uses the presence of
    LBMS bit as one of the triggering conditions, effectively monopolizing the
    use of that bit. An upcoming change will introduce a PCIe bandwidth
    controller which sets up an interrupt to track LBMS. As LBMS will be
    cleared by the interrupt handler, the Target Speed quirk will no longer be
    able to observe LBMS directly.

    As a preparatory step for the change, extract the LBMS seen check from
    pcie_failed_link_retrain() into a new function pcie_lmbs_seen().

    Link: https://lore.kernel.org/r/20241018144755.7875-6-ilpo.jarvinen@linux.intel.com


Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

Signed-off-by: Myron Stowe <mstowe@redhat.com>