usb: don't enter usb subdirectories directly

Instead, make we enter usb/ directory on all
needed cases and enter the subdirectories from
drivers/usb/Makefile.

Signed-off-by: Felipe Balbi <balbi@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
diff --git a/drivers/usb/Makefile b/drivers/usb/Makefile
index 239f050..9bc8aeb 100644
--- a/drivers/usb/Makefile
+++ b/drivers/usb/Makefile
@@ -45,3 +45,8 @@
 
 obj-$(CONFIG_USB_ATM)		+= atm/
 obj-$(CONFIG_USB_SPEEDTOUCH)	+= atm/
+
+obj-$(CONFIG_USB_MUSB_HDRC)	+= musb/
+obj-$(CONFIG_USB_RENESAS_USBHS)	+= renesas_usbhs/
+obj-$(CONFIG_USB_OTG_UTILS)	+= otg/
+obj-$(CONFIG_USB_GADGET)	+= gadget/