staging: vchiq_core: Don't BUG if process is unexpected

Bail out properly if the process index doesn't match the remote insert.
We also drop the BUG in case the process index is at local insert,
so we can trigger the WARN_ON again some steps later.

Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>