TCPMv2: Cache VDM response body between PE runs
TCPMv2: Cache VDM response body between PE runs

After parsing in PE_VDM_SEND_REQUEST, store the VDM response in PE
state. The VDM child states need to access the response, and the PRL may
overwrite its copy before the child runs.

BUG=none
TEST=Enter DP mode with partner that sends Attention quickly after DP
Configure ACK
BRANCH=none

Signed-off-by: Abe Levkoy <2e1ad7039298f93262cf06bbb457275fb3e2ecb5@chromium.org>
Change-Id: I1522c9510f4fd276a5d1e92b5641424b0f466845
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/2285430
Reviewed-by: Denis Brockus <6b21e8190fb5e373363fb95271367073a16474ef@chromium.org>
Reviewed-by: Diana Z <cb2016afc7183e5356c690dc63b4ba817470501a@chromium.org>
Tested-by: Denis Brockus <6b21e8190fb5e373363fb95271367073a16474ef@chromium.org>
Commit-Queue: Denis Brockus <6b21e8190fb5e373363fb95271367073a16474ef@chromium.org>

coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec