USB: add siemens_mpi usb-serial "stub" driver

This driver got rescued from a few years ago and was requested to be
added.  So I cleaned it up, ported it to the latest kernel version and
here it is.

Cc: Thomas Hergenhahn <thomas.hergenhahn@suse.de>
Cc: Emmanuele <iemmav@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/usb/serial/Kconfig b/drivers/usb/serial/Kconfig
index da30784..b361f05 100644
--- a/drivers/usb/serial/Kconfig
+++ b/drivers/usb/serial/Kconfig
@@ -496,6 +496,14 @@
 	bool "USB Secure Encapsulated Driver - Padded"
 	depends on USB_SERIAL_SAFE
 
+config USB_SERIAL_SIEMENS_MPI
+	tristate "USB Siemens MPI driver"
+	help
+	  Say M here if you want to use a Siemens USB/MPI adapter.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called siemens_mpi.
+
 config USB_SERIAL_SIERRAWIRELESS
 	tristate "USB Sierra Wireless Driver"
 	help