linux-ramdump-parser-v2: Update vmalloc parsing for all cases

The way the vmalloc list is walked has changed to use a different
structure. The old structure is now freed at init time. This may
not be noticed if init memory isn't freed. Switch to a method that
does not rely on not freeing initmem.

Change-Id: I9f9b095ac4740ff13c1f54e39c641f286941a63f