r8169: remove rtl_hw_start_8168dp

We can remove rtl_hw_start_8168dp() because it's the same as
rtl_hw_start_8168dp() now.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>