Fix weird change of volume status in re-scheduling

Fix weird change of volume status in re-scheduling

When create a volume failed as some exception, cinder will re-schedule the
creation request, the retry number is 3 in default.
But when re-scheduling, this volume's status was changed like this:

creating ----> error -----> creating------>error------>error/available

This is weird to user, since if this volume is in re-scheduling process,
it's status should always be creating, and then become error or available
at last.

Change-Id: I7a2d40585b5ef515a9400349a1397cba63278c78
Closes-Bug: #1445601