ramips: awake rt305x USB controller

Because of Ralink uboot set USB controller into sleep mode [1]
we check it and awake controller before any registers access.
Fix ticket #21396 [2]

[1] http://marc.info/?l=linux-usb&m=137398626102108&w=2
[2] https://dev.openwrt.org/ticket/21396

Signed-Off-By: Serge Vasilugin <vasilugin@yandex.ru>

SVN-Revision: 49212

target/linux/ramips/patches-4.4/0069-awake-rt305x-dwc2-controller.patch

@@ -0,0 +1,15 @@
+--- a/drivers/usb/dwc2/platform.c
++++ b/drivers/usb/dwc2/platform.c
+@@ -375,6 +375,12 @@ static int dwc2_driver_probe(struct plat
+ dev_dbg(&dev->dev, "mapped PA %08lx to VA %p\n",
+ (unsigned long)res->start, hsotg->regs);
+ 
++ /* Enable USB port before any regs access */
++ if(dwc2_readl(hsotg->regs + PCGCTL) & 0x0f) {
++ dwc2_writel(0x00, hsotg->regs + PCGCTL);
++ /* TODO: mdelay(25) here? vendor driver don't use it */
++ }
++
+ hsotg->dr_mode = usb_get_dr_mode(&dev->dev);
+ if (IS_ENABLED(CONFIG_USB_DWC2_HOST) &&
+ hsotg->dr_mode != USB_DR_MODE_HOST) {