tpm: report driver error code to upper layer

Instead of returning a generic 'library' error, report back the actual
error code so it can be displayed to the user by the regular error path.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Tom Rini <trini@konsulko.com>