Staging: keucr: prevent the driver from being built as a module.

As there are symbols that conflict with the in-kernel usb-storage
module, we can't build this into the kernel.
Reported-by: Randy Dunlap <randy.dunlap@oracle.com>
Cc: Al Cho <acho@novell.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/staging/keucr/Kconfig

 config USB_ENESTORAGE
 	tristate "USB ENE card reader support"
-	depends on USB && SCSI
+	depends on USB && SCSI && m
 	---help---
 	  Say Y here if you wish to control a ENE Card reader.