serial/8250_pci: simplify Pericom handling

Considering that pci_pericom_setup(()'s only difference to
pci_default_setup() is the setting of the uartclk field, and taking
into account that this field already gets taken care of by having the
base_baud field filled in the pci_boards[] entries, there's no need
for both the function and the quirks table entry.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>