Add VbSharedData field parsing

R=reinauer@chromium.org
BUG=chrome-os-partner:2578
TEST=manual

crossystem vdat_timers
should show 'LFS=0,0 LF=number1,number2 LK=number3,number4'
where number1 < number2 < number3 < number4

crossystem vdat_lfdebug
run from a dev mode console, should show
'check=12,0 index=0x00 tpmver=(hex number) lowestver=(hex number)'

crossystem vdat_flags
run from a dev mode console, flags should be 0x04.

Review URL: http://codereview.chromium.org/6685068

Change-Id: Id7b958ae300d10cdcdc1b17a1bb17b7e5069166f
8 files changed