usb: dwc3-meson-g12a: fix usb2 PHY glue init when phy0 is disabled

When only PHY1 is used (for example on Odroid-HC4), the regmap init code
uses the usb2 ports when doesn't initialize the PHY1 regmap entry.

This fixes:
Unable to handle kernel NULL pointer dereference at virtual address 0000000000000020
...
pc : regmap_update_bits_base+0x40/0xa0
lr : dwc3_meson_g12a_usb2_init_phy+0x4c/0xf8
...
Call trace:
regmap_update_bits_base+0x40/0xa0
dwc3_meson_g12a_usb2_init_phy+0x4c/0xf8
dwc3_meson_g12a_usb2_init+0x7c/0xc8
dwc3_meson_g12a_usb_init+0x28/0x48
dwc3_meson_g12a_probe+0x298/0x540
platform_probe+0x70/0xe0
really_probe+0xf0/0x4d8
driver_probe_device+0xfc/0x168
...

Fixes: 013af227 ("usb: dwc3: meson-g12a: handle the phy and glue registers separately")
Reviewed-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Cc: stable <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20210601084830.260196-1-narmstrong@baylibre.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/dwc3/dwc3-meson-g12a.c

@@ -651,7 +651,7 @@ static int dwc3_meson_g12a_setup_regmaps(struct dwc3_meson_g12a *priv,
 		return PTR_ERR(priv->usb_glue_regmap);
 
 	/* Create a regmap for each USB2 PHY control register set */
-	for (i = 0; i < priv->usb2_ports; i++) {
+	for (i = 0; i < priv->drvdata->num_phys; i++) {
 		struct regmap_config u2p_regmap_config = {
 			.reg_bits = 8,
 			.val_bits = 32,
@@ -659,6 +659,9 @@ static int dwc3_meson_g12a_setup_regmaps(struct dwc3_meson_g12a *priv,
 			.max_register = U2P_R1,
 		};
 
+		if (!strstr(priv->drvdata->phy_names[i], "usb2"))
+			continue;
+
 		u2p_regmap_config.name = devm_kasprintf(priv->dev, GFP_KERNEL,
 							"u2p-%d", i);
 		if (!u2p_regmap_config.name)