net: dsa: mt7530: move XTAL check to mt7530_setup()

The crystal frequency concerns the switch core. The frequency should be
checked when the switch is being set up so the driver can reject the
unsupported hardware earlier and without requiring port 6 to be used.

Move it to mt7530_setup(). Drop the unnecessary function printing.
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Vladimir Oltean <olteanv@gmail.com>
Reviewed-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Signed-off-by: Arınç ÜNAL <arinc.unal@arinc9.com>
Link: https://lore.kernel.org/r/20240206-for-netnext-mt7530-improvements-2-v5-2-d7d92a185cb1@arinc9.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/dsa/mt7530.c

@@ -422,13 +422,6 @@ mt7530_pad_clk_setup(struct dsa_switch *ds, phy_interface_t interface)
 
 	xtal = mt7530_read(priv, MT7530_MHWTRAP) & HWTRAP_XTAL_MASK;
 
-	if (xtal == HWTRAP_XTAL_20MHZ) {
-		dev_err(priv->dev,
-			"%s: MT7530 with a 20MHz XTAL is not supported!\n",
-			__func__);
-		return -EINVAL;
-	}
-
 	switch (interface) {
 	case PHY_INTERFACE_MODE_RGMII:
 		trgint = 0;
@@ -2259,6 +2252,12 @@ mt7530_setup(struct dsa_switch *ds)
 		return -ENODEV;
 	}
 
+	if ((val & HWTRAP_XTAL_MASK) == HWTRAP_XTAL_20MHZ) {
+		dev_err(priv->dev,
+			"MT7530 with a 20MHz XTAL is not supported!\n");
+		return -EINVAL;
+	}
+
 	/* Reset the switch through internal reset */
 	mt7530_write(priv, MT7530_SYS_CTRL,
 		     SYS_CTRL_PHY_RST | SYS_CTRL_SW_RST |