usb: dwc3: core: Fix tx/rx threshold settings

The current driver logic checks against 0 to determine whether the
periodic tx/rx threshold settings are set, but we may get bogus values
from uninitialized variables if no device property is set. Properly
default these variables to 0.

Fixes: 938a5ad1 ("usb: dwc3: Check for ESS TX/RX threshold config")
Cc: <stable@vger.kernel.org>
Signed-off-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com>
Link: https://lore.kernel.org/r/cccfce990b11b730b0dae42f9d217dc6fb988c90.1649727139.git.Thinh.Nguyen@synopsys.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/dwc3/core.c

@@ -1377,10 +1377,10 @@ static void dwc3_get_properties(struct dwc3 *dwc)
 	u8			lpm_nyet_threshold;
 	u8			tx_de_emphasis;
 	u8			hird_threshold;
-	u8			rx_thr_num_pkt_prd;
-	u8			rx_max_burst_prd;
-	u8			tx_thr_num_pkt_prd;
-	u8			tx_max_burst_prd;
+	u8			rx_thr_num_pkt_prd = 0;
+	u8			rx_max_burst_prd = 0;
+	u8			tx_thr_num_pkt_prd = 0;
+	u8			tx_max_burst_prd = 0;
 	u8			tx_fifo_resize_max_num;
 	const char		*usb_psy_name;
 	int			ret;