west.yml: MCUboot synchronization from upstream

Update Zephyr fork of MCUboot to revision:
  0c0470e294dcfb52aab92299356a5f3caa0aa52b

Brings following Zephyr relevant fixes:
 - e9fccef5 boot_serial: Fix missing response if echo command
   disabled
 - 013c9e76 boot: zephyr: board: various: Remove size optimisation
 - 0a8bbbf4 boot: zephyr: Fix USB configs
 - d5c963c5 boot: zephyr: serial_adapter: Add error if main thread
   not preemptible
 - 822b6cb7 boot: zephyr: serial_adapter: Fail if USB CDC enabled
   with console

Signed-off-by: Jamie McCrae <jamie.mccrae@nordicsemi.no>