net: dsa: mt7530: do not use SW_PHY_RST to reset MT7531 switch

According to the document MT7531 Reference Manual for Development Board
v1.0, the SW_PHY_RST bit on the SYS_CTRL register doesn't exist for
MT7531. This is likely why forcing link down on all ports is necessary for
MT7531.

Therefore, do not set SW_PHY_RST on mt7531_setup().
Signed-off-by: Arınç ÜNAL <arinc.unal@arinc9.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

drivers/net/dsa/mt7530.c

@@ -2451,14 +2451,12 @@ mt7531_setup(struct dsa_switch *ds)
 	val = mt7530_read(priv, MT7531_TOP_SIG_SR);
 	priv->p5_sgmii = !!(val & PAD_DUAL_SGMII_EN);
 
-	/* all MACs must be forced link-down before sw reset */
+	/* Force link down on all ports before internal reset */
 	for (i = 0; i < MT7530_NUM_PORTS; i++)
 		mt7530_write(priv, MT7530_PMCR_P(i), MT7531_FORCE_LNK);
 
 	/* Reset the switch through internal reset */
-	mt7530_write(priv, MT7530_SYS_CTRL,
-		     SYS_CTRL_PHY_RST | SYS_CTRL_SW_RST |
-		     SYS_CTRL_REG_RST);
+	mt7530_write(priv, MT7530_SYS_CTRL, SYS_CTRL_SW_RST | SYS_CTRL_REG_RST);
 
 	if (!priv->p5_sgmii) {
 		mt7531_pll_setup(priv);