Fix possible memory leak in phyp_driver.c

Fix possible memory leak in phyp_driver.c

There could be a memory leak caused by "managed_system" string, if any
error occurs before "managed_system" is assigned into
"phyp_driver->managed_system". The "managed_system" string wouldn't be
freed at all. The better way is to free the "managed_system" instead
of the one assigned in the "phyp_driver".

This has been found by coverity.

Pointed out by John, that the "phyp_driver->xmlopt" needs to be
unreferenced as well.

Signed-off-by: Pavel Hrdina <phrdina@redhat.com>
Signed-off-by: John Ferlan <jferlan@redhat.com>