serial: 8250_pci: Drop bogus __refdata annotation

Since commit d73dfc6a ("serial: 8250_pci: remove __devexit
usage") in v3.9, the 8250/16550 PCI serial driver no longer has any code
or data located in initmem, hence there is no need to annotate the
pci_serial_quirks structure with __refdata.  Drop the annotation, to
avoid suppressing future section warnings.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/20201211133907.2970460-1-geert+renesas@glider.be


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>