USB: Allow usbmon as a module even if usbcore is builtin

usbmon can only be built as a module if usbcore is a module too. Trivial
changes to the relevant Kconfig and Makefile (and a few trivial changes
elsewhere) allow usbmon to be built as a module even if usbcore is
builtin.

This is verified to work in all 9 permutations (3 correctly prohibited
by Kconfig, 6 build a suitable result).

Signed-off-by: Paul Bolle <pebolle@tiscali.nl>
Signed-off-by: Pete Zaitcev <zaitcev@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/usb/mon/Makefile b/drivers/usb/mon/Makefile
index 0f76ed5..c6516b5 100644
--- a/drivers/usb/mon/Makefile
+++ b/drivers/usb/mon/Makefile
@@ -4,5 +4,4 @@
 
 usbmon-objs	:= mon_main.o mon_stat.o mon_text.o mon_bin.o mon_dma.o
 
-# This does not use CONFIG_USB_MON because we want this to use a tristate.
-obj-$(CONFIG_USB)	+= usbmon.o
+obj-$(CONFIG_USB_MON)	+= usbmon.o