ha: Properly initialize algo variables when installing CHILD_SAs

ha: Properly initialize algo variables when installing CHILD_SAs

If AEAD algorithms are used no integrity algorithm will be received from
the other HA node.  But since AUTH_UNDEFINED is 1024 and not 0 this value
was incorrectly added to the proposal, resulting in a failure during key
derivation.  The variables are now explicitly initialized to 0, as already
was the case for the IKE SAs.

Fixes #1051.