[COMMON] Fix condition equality bashisms

pointed out by checkbashisms.

$ mycmd=$(tox -e checkbashisms | grep "(should be 'b = a')" | sed -e
  "s@^[^.]*\(.[^ ]*\) line \([0-9]*\) .*@sed -i -e '\2s/==/=/g' \1;@")

$ eval $mycmd

Issue-ID: OOM-2643
Signed-off-by: Guillaume Lambert <guillaume.lambert@orange.com>
Change-Id: I9032130bc4717e111de11a73187c2f1052376e45
diff --git a/kubernetes/sdnc/components/sdnc-prom/resources/bin/prom.sh b/kubernetes/sdnc/components/sdnc-prom/resources/bin/prom.sh
index 7764d00..fa76a9e 100755
--- a/kubernetes/sdnc/components/sdnc-prom/resources/bin/prom.sh
+++ b/kubernetes/sdnc/components/sdnc-prom/resources/bin/prom.sh
@@ -24,7 +24,7 @@
 
 # should PROM start as passive?
 state=$( bin/sdnc.cluster )
-if [ "$state" == "standby" ]; then
+if [ "$state" = "standby" ]; then
   echo "Starting PROM in passive mode"
   passive="-p"
 fi