usb: dwc3: Use of_property_read_variable_u32_array() to read "power"

There's no need to get the length of an DT array property before
parsing the array. of_property_read_variable_u32_array() takes a minimum
and maximum length and returns the actual length (or error code).

This is part of a larger effort to remove callers of of_find_property()
and similar functions. of_find_property() leaks the DT struct property
and data pointers which is a problem for dynamically allocated nodes
which may be freed.

Signed-off-by: Rob Herring (Arm) <[e-mail]>
Acked-by: Thinh Nguyen <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/usb/dwc3/dwc3-octeon.c

···
 	int ref_clk_sel, ref_clk_fsel, mpll_mul;
 	int power_active_low, power_gpio;
 	int err, len;
-	u32 clock_rate;
+	u32 clock_rate, gpio_pwr[3];
 
 	if (of_property_read_u32(node, "refclk-frequency", &clock_rate)) {
 		dev_err(dev, "No UCTL \"refclk-frequency\"\n");
···
 
 	power_gpio = DWC3_GPIO_POWER_NONE;
 	power_active_low = 0;
-	if (of_find_property(node, "power", &len)) {
-		u32 gpio_pwr[3];
-
-		switch (len) {
-		case 8:
-			of_property_read_u32_array(node, "power", gpio_pwr, 2);
-			break;
-		case 12:
-			of_property_read_u32_array(node, "power", gpio_pwr, 3);
+	len = of_property_read_variable_u32_array(node, "power", gpio_pwr, 2, 3);
+	if (len > 0) {
+		if (len == 3)
 			power_active_low = gpio_pwr[2] & 0x01;
-			break;
-		default:
-			dev_err(dev, "invalid power configuration\n");
-			return -EINVAL;
-		}
 		power_gpio = gpio_pwr[1];
 	}