vboot: cgpt: Refer to partition entries by entries_lba.

This CL accesses the partition entry array through its header's
entries_lba value.

Previously, we assume the primary entry array lies on third sector, and
the secondary array lies (1 + 32) sectors from disk end. This assumption
was fine, even Wikipedia assumed the same.

But in order for us to support writing boot code to the third sector (as
required by some Freescale board), the primary entry array must be moved
to another location. Therefore, we must use "entries_lba" to locate the
arrays from now on.

TEST=`cgpt create -p` and then `cgpt show`. Make sure the table
     header and entries are properly moved.

Change-Id: Ia9008b0bb204f290b1f6240df562ce7d3a9bbff2
Reviewed-on: https://chromium-review.googlesource.com/213861
Reviewed-by: Bill Richardson <wfrichar@chromium.org>
Tested-by: Bill Richardson <wfrichar@chromium.org>
Commit-Queue: Nam Nguyen <namnguyen@chromium.org>
Tested-by: Nam Nguyen <namnguyen@chromium.org>
9 files changed