net: switch to the kernel.org patchwork instance

Move to the kernel.org patchwork instance, it has significantly
lower latency for accessing from Europe and the US. Other quirks
include the reply bot.

Link: https://lore.kernel.org/r/20201110035120.642746-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>