west.yml: Update mcumgr revision

Commits affecting Zephyr that are included with the new revision:
    47fdde0 Fix missing else in configuration;
    30cf9fe zephyr: Fix BUILD_ASSERT failing build with correct number
            of images.

Signed-off-by: Dominik Ermel <dominik.ermel@nordicsemi.no>
Signed-off-by: Anas Nashif <anas.nashif@intel.com>