USB: regroup all depends on USB within an if USB block

This patch removes the depends on USB from all config symbols in
drivers/usb/host/Kconfig and replace that with an if USB / endif block
as suggested by Alan Stern. Some source ... Kconfig lines have been
shuffled around to permit a better regroupment of the Kconfig files
depending on "config USB" item. No functionnal change is introduced.

Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Florian Fainelli <florian@openwrt.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/usb/atm/Kconfig b/drivers/usb/atm/Kconfig
index be0b8da..0f92294 100644
--- a/drivers/usb/atm/Kconfig
+++ b/drivers/usb/atm/Kconfig
@@ -4,7 +4,7 @@
 
 menuconfig USB_ATM
 	tristate "USB DSL modem support"
-	depends on USB && ATM
+	depends on ATM
 	select CRC32
 	default n
 	help