Changes

vty: Prohibit confiruing an IPA ASP as IPSP

We could eventually define how the IPA CCM is expected to behave when in
IPSP role (eg. implementing/allowing both sides of IPA CCM, or assigning
an IPA CCM role based on TCP client/server), but that has not yet been
defined.

IPSP is actually a good candidate for IPA ASPs, since in IPA proto we
don't have SNM messaging either, and it's meant to be used
point-to-point (or through STP by assigning hardocded routes).

Change-Id: I18ad3e9ad4aac7a3d8e84483ba1bf09016520b54