usb: common: rework CONFIG_USB_COMMON logic

The phy-am335x driver selects 'USB_COMMON', but all other drivers
use 'depends on' for that symbol, and it depends on USB || USB_GADGET
itself, which causes a Kconfig warning:

warning: (AM335X_PHY_USB) selects USB_COMMON which has unmet direct dependencies (USB_SUPPORT && (USB || USB_GADGET))

As suggested by Felipe Balbi, this turns the logic around, and makes
'USB_COMMON' selected by everything else that needs it, so we can
remove the dependencies.

Fixes: 59f042f644c5 ("usb: phy: phy-am335x: bypass first VBUS sensing for host-only mode")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Felipe Balbi <balbi@kernel.org>
Reviewed-by: Peter Chen <peter.chen@nxp.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
diff --git a/drivers/usb/Kconfig b/drivers/usb/Kconfig
index 8ed451d..8689dcb 100644
--- a/drivers/usb/Kconfig
+++ b/drivers/usb/Kconfig
@@ -31,8 +31,6 @@
 
 config USB_COMMON
 	tristate
-	default y
-	depends on USB || USB_GADGET
 
 config USB_ARCH_HAS_HCD
 	def_bool y
@@ -41,6 +39,7 @@
 config USB
 	tristate "Support for Host-side USB"
 	depends on USB_ARCH_HAS_HCD
+	select USB_COMMON
 	select NLS  # for UTF-8 strings
 	---help---
 	  Universal Serial Bus (USB) is a specification for a serial bus