west.yml: MCUboot synchronization from upstream

Update Zephyr fork of MCUboot to revision:
  bf8cf46b348eb8c8c10a1f1e4a7c24cdef52acf0

Brings following Zephyr relevant fixes:
 - 2929a975 bootutil: Show error if flash area open fails

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