tpm: Fix return type of unmarshal_u32

The return type of the function is wrong, it results in truncation of
the unmarshalled value.

BRANCH=none
BUG=none
TEST=verified proper display of the TPM error code

Change-Id: I44844309b1ddfbc91a8fdf8897ccc88be1aaa164
Signed-off-by: Vadim Bendebury <vbendeb@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/536193
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-by: Furquan Shaikh <furquan@chromium.org>
(cherry picked from commit c76eca10663fcbf1b8e61b2fd84ff95b29a30800)
Reviewed-on: https://chromium-review.googlesource.com/536177
1 file changed