optee-client: Add sysVinit service

Adds a sysVinit service to start tee-supplicant so that the optee-client
package can be used on distros where systemd is not used. Also does some
cleanup of the recipe including:
 1) Using @path@ tokens for replacemane in the .service file instead of
    paths
 2) Replacing tokens in the .service file after it is installed instead
    of editing the source file in ${WORKDIR}

Signed-off-by: Joshua Watt <JPEWhacker@gmail.com>
Reviewed-by: Diego Sueiro <diego.sueiro@arm.com>
Reviewed-by: Denys Dmytriyenko <denys@ti.com>
Signed-off-by: Jon Mason <jon.mason@arm.com>