net: dsa: mt7530: setup core clock even in TRGMII mode

A recent change to MIPS ralink reset logic made it so mt7530 actually
resets the switch on platforms such as mt7621 (where bit 2 is the reset
line for the switch). That exposed an issue where the switch would not
function properly in TRGMII mode after a reset.

Reconfigure core clock in TRGMII mode to fix the issue.

Tested on Ubiquiti ER-X (MT7621) with TRGMII mode enabled.

Fixes: 3f9ef778 ("MIPS: ralink: manage low reset lines")
Signed-off-by: Ilya Lipnitskiy <ilya.lipnitskiy@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>