usb: dwc3: Fix default lpm_nyet_threshold value

BugLink: https://bugs.launchpad.net/bugs/1830176

commit 8d791929 upstream.

The max possible value for DCTL.LPM_NYET_THRES is 15 and not 255. Change
the default value to 15.

Cc: stable@vger.kernel.org
Fixes: 80caf7d2 ("usb: dwc3: add lpm erratum support")
Signed-off-by: Thinh Nguyen <thinhn@synopsys.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Juerg Haefliger <juergh@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

drivers/usb/dwc3/core.c

@@ -867,7 +867,7 @@ static int dwc3_probe(struct platform_device *pdev)
 	dwc->regs_size	= resource_size(res);
 
 	/* default to highest possible threshold */
-	lpm_nyet_threshold = 0xff;
+	lpm_nyet_threshold = 0xf;
 
 	/* default to -3.5dB de-emphasis */
 	tx_de_emphasis = 1;