kernel: bump 4.9 to 4.9.175

Refreshed all patches.

Compile-tested on: ar71xx
Runtime-tested on: ar71xx

Signed-off-by: Koen Vandeputte <koen.vandeputte@ncentric.com>

target/linux/brcm2708/patches-4.9/950-0031-Add-dwc_otg-driver.patch

@@ -707,7 +707,7 @@ Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
  		msleep(100);	/* Cool down */
 --- a/drivers/usb/core/message.c
 +++ b/drivers/usb/core/message.c
-@@ -1922,6 +1922,85 @@ free_interfaces:
+@@ -1924,6 +1924,85 @@ free_interfaces:
  	if (cp->string == NULL &&
  			!(dev->quirks & USB_QUIRK_CONFIG_INTF_STRINGS))
  		cp->string = usb_cache_string(dev, cp->desc.iConfiguration);