usb: musb: Rework USB and USB_GADGET dependency

This USB controller can work in as host-only, gadget-only or dual-role
modes. Rework the dependency on the USB and USB_GADGET configs in order
to allow building the driver when !USB or !USG_GADGET.

Signed-off-by: Ezequiel Garcia <ezequiel.garcia@free-electrons.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>
diff --git a/drivers/usb/Kconfig b/drivers/usb/Kconfig
index 2642b8a..a34fb98 100644
--- a/drivers/usb/Kconfig
+++ b/drivers/usb/Kconfig
@@ -94,8 +94,6 @@
 
 source "drivers/usb/host/Kconfig"
 
-source "drivers/usb/musb/Kconfig"
-
 source "drivers/usb/renesas_usbhs/Kconfig"
 
 source "drivers/usb/class/Kconfig"
@@ -106,6 +104,8 @@
 
 endif
 
+source "drivers/usb/musb/Kconfig"
+
 source "drivers/usb/dwc3/Kconfig"
 
 source "drivers/usb/chipidea/Kconfig"