EDAC/ie31200: Fallback if host bridge device is already initialized

The Intel uncore driver may claim some of the pci ids from ie31200 which
means that the ie31200 edac driver will not initialize them as part of
pci_register_driver().

Let's add a fallback for this case to 'pci_get_device()' to get a
reference on the device such that it can still be configured. This is
similar in approach to other edac drivers.

Signed-off-by: Jason Baron <jbaron@akamai.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Mauro Carvalho Chehab <mchehab@kernel.org>
Cc: linux-edac <linux-edac@vger.kernel.org>
Signed-off-by: Tony Luck <tony.luck@intel.com>
Link: https://lore.kernel.org/r/1594923911-10885-1-git-send-email-jbaron@akamai.com