usb: dwc3: keep default hird threshold value as 4b1100

as per data book any HIRD threshold value greater than 4b1100 is
invalid. So set the maximum valid value as default values.
Signed-off-by: Pratyush Anand <pratyush.anand@st.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

drivers/usb/dwc3/gadget.c

@@ -2448,7 +2448,7 @@ int __devinit dwc3_gadget_init(struct dwc3 *dwc)
 		reg &= ~(DWC3_DCTL_HIRD_THRES_MASK | DWC3_DCTL_L1_HIBER_EN);
 
 		/* TODO: This should be configurable */
-		reg |= DWC3_DCTL_HIRD_THRES(31);
+		reg |= DWC3_DCTL_HIRD_THRES(28);
 
 		dwc3_writel(dwc->regs, DWC3_DCTL, reg);