Previously quirk_paxc_bridge() was applied when the iproc driver was
built-in, but not when it was compiled as a module.

This happened because it was under #ifdef CONFIG_PCIE_IPROC_PLATFORM:
PCIE_IPROC_PLATFORM=y causes CONFIG_PCIE_IPROC_PLATFORM to be defined, but
PCIE_IPROC_PLATFORM=m causes CONFIG_PCIE_IPROC_PLATFORM_MODULE to be
defined.

Move quirk_paxc_bridge() to pcie-iproc.c and drop the #ifdef so the quirk
is always applied, whether iproc is built-in or a module.

[bhelgaas: commit log, move to pcie-iproc.c, not pcie-iproc-platform.c]
Link: https://lore.kernel.org/r/20191211174511.89713-1-wei.liu@kernel.orgSigned-off-by: Wei Liu <wei.liu@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>