cca-workload-attestation: Set fixed version

Since we're about to update the tool, use a fixed version for this
legacy branch of cca-buildroot-external

Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>

package/cca-workload-attestation/cca-workload-attestation.mk

@@ -4,7 +4,7 @@
 #
 ################################################################################
 
-CCA_WORKLOAD_ATTESTATION_VERSION = clo/main
+CCA_WORKLOAD_ATTESTATION_VERSION = 5f924bc
 CCA_WORKLOAD_ATTESTATION_SITE = https://git.codelinaro.org/linaro/dcap/cca-demos/cca-workload-attestation-poc.git
 CCA_WORKLOAD_ATTESTATION_SITE_METHOD = git
 CCA_WORKLOAD_ATTESTATION_LICENSE = BSD 3-Clause