bfd: schema: fix a typo in ietf-bfd-schema

The typo broke scons controller/src/schema, but compiling controller by running
scons without arguments did not catch the error.

Change-Id: I9d71707b9d07a1773a760376646118a993e3ee17
Signed-off-by: Mateusz Zalega <mateusz.zalega@codilime.com>
Merge "bfd: schema: fix a typo in ietf-bfd-schema"