PCI hotplug: fix typo in pcie link speed info

Fix typo in PCI-E link speed.

Reviewed-by: Matthew Wilcox <matthew@wil.cx>
Signed-off-by: Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>