Pure's "pure_host_personality" configuration option currently defaults
to a non valid value according to its choices.
This affects tools leveraging the "get_driver_options" mechanism, since
the default value for the option was not considered a valid option.
This patch sets the default explicitly and adds it as a valid choice.
Change-Id: I381b80920d812a3f3b5f75b6dae66aa932f6baa4
(cherry picked from commit 69f4f5ffe4)
e20c7d34e4