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>
SVN-Revision: 46222