Remove unused 3PAR driver method

Remove the "parse_create_host_error" method as it is no longer
used in the 3PAR drivers. It can safely be removed from the
3PAR common code and the unit test were no longer using the method.

Change-Id: I81898e075107b55002c2d07f5e06db76a16c3e28
Closes-bug: 1310807
Merge "Remove unused 3PAR driver method"