serial:8250:8250_pci: fix redundant entry report for WCH_CH352_2S

Commit 8b5c913f
("serial: 8250_pci: Add WCH CH352 quirk to avoid Xscale detection")
trigger one redundant entry report message.

This patch fix it.

Reported-by: Russell King <rmk@arm.linux.org.uk>
Signed-off-by: Wang YanQing <udknight@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>