updater_utils: fix implicit conversion to enum wp_state

The getter for HWWP implicitly converted the integer returned by
crossystem to an `enum wp_state`. This only worked because of the
particular values assigned to the enum values, so explicitly convert
instead.

BUG=b:223291615
BRANCH=none
TEST=builds

Change-Id: Ib572733f8b05a5a992f09ba98050a7eab5e3bcce
Signed-off-by: Nikolai Artemiev <nartemiev@google.com>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/vboot_reference/+/3540784
Reviewed-by: Julius Werner <jwerner@chromium.org>
Reviewed-by: Edward O'Callaghan <quasisec@chromium.org>
Tested-by: Edward O'Callaghan <quasisec@chromium.org>
1 file changed