x86/oprofile: fix pci_dev use count for AMD northbridge devices

This patch fixes the PCI device use count for AMD northbridge
devices. In case of an IBS LVT initialization failure, the PCI device
is released now by calling pci_dev_put().

If there are no initialization errors, the devices are released in
pci_get_device() while iterating.

Signed-off-by: Robert Richter <robert.richter@amd.com>