tpm2_getmanufec: simplify execute_tool() error codes propagation
tpm2_getmanufec: simplify execute_tool() error codes propagation

The tool main function that calls execute_tool() doesn't use the returned
value, it only takes 0 as a succeeds value an everything else as an error.

So lets just return consistently 1 as an error an 0 as a success, instead
of returning a combination of -1 and value set in the return_val variable.

Signed-off-by: Javier Martinez Canillas <8fdf2abf85d34ea8f3f979ef25dc1f25d94aca29@redhat.com>

01org/tpm2.0-tools,martinezjavier/tpm2-tools,martinezjavier/tpm2-tools,martinezjavier/tpm2-tools,martinezjavier/tpm2-tools,01org/tpm2.0-tools,01org/tpm2.0-tools