PCI: dwc: Fix n_fts[] array overrun

PCI: dwc: Fix n_fts[] array overrun

commit aeaa0bfe89654 ("PCI: dwc: Move N_FTS setup to common setup")
incorrectly uses pci->link_gen in deriving the index to the
n_fts[] array also introducing the issue of accessing beyond the
boundaries of array for greater than Gen-2 speeds. This change fixes
that issue.

Link: https://lore.kernel.org/r/20220926111923.22487-1-vidyas@nvidia.com
Fixes: aeaa0bfe8965 ("PCI: dwc: Move N_FTS setup to common setup")
Signed-off-by: Vidya Sagar <vidyas@nvidia.com>
Signed-off-by: Lorenzo Pieralisi <lpieralisi@kernel.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Acked-by: Jingoo Han <jingoohan1@gmail.com>