Added methods:-
get_persistent_boot_device()
update_persistent_boot()
get_one_time_boot()
set_one_time_boot()
Removed these methods from IloClient as they are not used
by drivers:-
get_persistent_boot()
set_persistent_boot()
Change-Id: I5e9b89e73d560404bc8395d029db8d2fd9fa64d2