lantiq: Silence the printk when a PCIe error interrupt arrives

Basically the only error I am seeing is "Correctable Error". Also newer
lantiq PCIe drivers have this message wrapped in a "if debug enabled"
block. So it should be safe to disable this warning.

Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@46222 3c298f89-4303-0410-b956-a3cf2f4a3e73