powerpc/fsl/pci: Fix when quirk_fsl_pcie_header is freed up

Change quirk_fsl_pcie_header from __init to __devinit to ensure if we
have a runtime access (like via an FPGA being loaded after boot on the
PCIe link) that we dont access randomly freed memory.

Signed-off-by: Matias Garcia <mgarcia@rossvideo.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>