MYNEWT-629: Unexpected advertising state machine stop.
MYNEWT-629: Unexpected advertising state machine stop.

This commit should fix the bug where an advertising state machine that
was not expected to be stopped could be stopped when a different
state machine was stopped through the hci advertising enable command.

This change does affect both MULTI_ADV_SUPPORT and normal builds.

X-Original-Commit: 1449ffcdbac75131f98f933036696427bbc3b57a

apache/mynewt-nimble,apache/mynewt-nimble,apache/mynewt-nimble,apache/mynewt-nimble,apache/mynewt-nimble