vbnv: Do not silently reset cache in read_vbnv

Currently, read_vbnv performs a reset of the vbnv cache if it is not
valid. However, this information is not passed up to the vboot layer,
thus resulting in missed write-back of vbnv cache to storage if vboot
does not update the cache itself.

Update read_vbnv to return a value depending upon whether it wants a
write-back to be performed when save is called.
Return value:
0 = No write-back required
1 = Write-back of VBNV cache is required.

Change-Id: I239939d5f9731d89a9d53fe662321b93fc1ab113
Signed-off-by: Furquan Shaikh <furquan@google.com>
Reviewed-on: https://review.coreboot.org/15457
Tested-by: build bot (Jenkins)
Reviewed-by: Aaron Durbin <adurbin@chromium.org>

0 files changed, 0 insertions, 0 deletions