serial: 8250_pci: Add support for Pericom PI7C9X795[1248]

Pericom PI7C9X795[1248] are Uno/Dual/Quad/Octal UART devices, this
patch enables them, also defines PCI_VENDOR_ID_PERICOM here.

Signed-off-by: Adam Lee <adam.lee@canonical.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>