There's no reason pci_uevent_ers() needs to be inline in pci.h, so move it
out to a C file.

Given it's used by AER the obvious location would be somewhere in
drivers/pci/pcie/aer, but because it's also used by powerpc EEH code
unfortunately that doesn't work in the case where EEH is enabled but
PCIEPORTBUS is not.

So for now put it in pci-driver.c, next to pci_uevent(), with an
appropriate #ifdef so it's not built if AER and EEH are both disabled.

While we're moving it also fix up the kernel doc comment for @pdev to be
accurate.
Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Bjorn Helgaas <helgaas@kernel.org>
Reviewed-by: Bryant G. Ly <bryantly@linux.vnet.ibm.com>