net: rtl8169: clean receive buffer after net handler
The processing of the buffer might change some data, which
will eventually trigger a cache writeback later on, corrupting
data written by the network chip. Clean the cache range
to make sure there is no writeback pending.
Signed-off-by: Lucas Stach <dev@lynxeye.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>