eclair/build-tfa.sh: Handle MAKE_JOBS envvar (from job params)

Pass it to -j, 3 is still the default.

Signed-off-by: Paul Sokolovsky <paul.sokolovsky@linaro.org>
Change-Id: Id94f68bc9a3afdeaeaa106261e77cf6003a39384
diff --git a/eclair/build-tfa.sh b/eclair/build-tfa.sh
index cdabead..fd6193f 100755
--- a/eclair/build-tfa.sh
+++ b/eclair/build-tfa.sh
@@ -15,4 +15,4 @@
 # Replace '$(PWD)' with the *current* $PWD.
 MAKE_TARGET=$(echo "${MAKE_TARGET}" | sed "s|\$(PWD)|$PWD|")
 
-make ${MAKE_TARGET} -j3 $(cat ${WORKSPACE}/tf-a-ci-scripts/tf_config/$1) DEBUG=${DEBUG}
+make ${MAKE_TARGET} -j${MAKE_JOBS:-3} $(cat ${WORKSPACE}/tf-a-ci-scripts/tf_config/$1) DEBUG=${DEBUG}