This commit enables support for using 'MAX' as a possible
value for size_gb for logical disks. When 'MAX' is used for
a logical disk, that logical disk is created last. The remaining
amount of space available is given to that logical disk. Multiple
logical disks with 'MAX' may be specified, but might not be an
actual use-case.
Change-Id: I1af332285251667a2d40b8854a4f3c36753a3322