r8169: simplify code by using core-provided pcpu stats allocation

Use core-provided pcpu stats allocation instead of open-coding it in
the driver.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Link: https://lore.kernel.org/r/03f5bb3b-d7f4-48be-ae8a-54862ec4566c@gmail.com


Signed-off-by: Paolo Abeni <pabeni@redhat.com>