Add pcie_get_speed_cap() to find the max link speed supported by a device.
Change max_link_speed_show() to use pcie_get_speed_cap().
Signed-off-by: NTal Gilboa <talgi@mellanox.com>
[bhelgaas: return speed directly instead of error and *speed, don't export
outside drivers/pci]
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
Reviewed-by: NTariq Toukan <tariqt@mellanox.com>