kmsan: export kmsan_handle_urb

USB support can be in a loadable module, and this causes a link failure
with KMSAN:

ERROR: modpost: "kmsan_handle_urb" [drivers/usb/core/usbcore.ko] undefined!

Export the symbol so it can be used by this module.

Link: https://lkml.kernel.org/r/20221215162710.3802378-1-arnd@kernel.org
Fixes: 553a80188a ("kmsan: handle memory sent to/from USB")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Marco Elver <elver@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/kmsan/hooks.c

@@ -260,6 +260,7 @@ void kmsan_handle_urb(const struct urb *urb, bool is_out)
 					       urb->transfer_buffer_length,
 					       /*checked*/ false);
 }
+EXPORT_SYMBOL_GPL(kmsan_handle_urb);
 
 static void kmsan_handle_dma_page(const void *addr, size_t size,
 				  enum dma_data_direction dir)