package/optee-benchmark: new package

package/optee-benchmark: new package

OP-TEE performance benchmark tools for the OP-TEE project.

This packages generates embedded Linux based OS materials used
to retrieve execution timing information on invocation of the
OP-TEE secure services.

It is added next to the OP-TEE client package in BR configuration.

This change references in Buildroot the today's latest OP-TEE
revision release tagged 3.4.0.

Signed-off-by: Etienne Carriere <etienne.carriere@linaro.org>
[Thomas:
 - drop version selection
 - propagate the dependency of optee-client]
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>