r8169: remove unused interrupt sources

Setting PCSTimeout interrupt source was copied from the vendor driver
which uses the chip programmable timer interrupt. The mainline driver
doesn't use this timer interrupt.

SYSErr indicates a PCI error and isn't defined on the PCIe models.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>