net: dsa: felix: use resolved link config in mac_link_up()

Phylink now requires that parameters established through
auto-negotiation be written into the MAC at the time of the
mac_link_up() callback. In the case of felix, that means taking the port
out of reset, setting the correct timers for PAUSE frames, and
enabling/disabling TX flow control.

This patch also splits the inband and noinband configuration of the
vsc9959 PCS (currently found in a function called "init") into 2
different functions, which have a nomenclature closer to phylink:
"config", for inband setup, and "link_up", for noinband (forced) setup.

This is necessary as a preparation step for giving up control of the PCS
to phylink, which will be done in further patch series.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>