realtek: eth: make hw_en_rxtx() a config member

realtek: eth: make hw_en_rxtx() a config member

Due to the last refactorings it has become clear that the following
code is wrong.

static void rteth_tx_timeout()
{
  ...
  rteth_838x_hw_en_rxtx(ctrl);

A generic function must not call a device specific function directly.
Make hw_en_rxtx() a config member and call that instead of the
functions directly.

With this change another optimization can take place. hw_init()
currently calls device specific hw_en_rxtx() functions at the start
of the function. This is wrong. Initialize the hardware first before
activating the network rx/tx. Take out the multiple calls and place
the rx/tx setup just before the hw_init() call.

Signed-off-by: Markus Stockhausen <markus.stockhausen@gmx.de>
Link: https://github.com/openwrt/openwrt/pull/22421
Signed-off-by: Robert Marko <robimarko@gmail.com>