LAVA: Deprecate param TARGET_PLATFORM

LAVA submit job has deprecated TARGET_PLATFORM and uses TFM_PLATFORM instead.

Signed-off-by: Xinyu Zhang <xinyu.zhang@arm.com>
Change-Id: Ia64c32f150daff246e7241070866889ff4713e3b
diff --git a/jenkins/lava-submit.jpl b/jenkins/lava-submit.jpl
index dfc02c5..89a114a 100644
--- a/jenkins/lava-submit.jpl
+++ b/jenkins/lava-submit.jpl
@@ -31,7 +31,7 @@
   // For AN521 builds running per-patch (started by the tf-m-static job),
   // run tests only on FVP to improve turnaround/performance.
   if (isPerPatchJob()) {
-    if (env.TARGET_PLATFORM == "AN521") {
+    if (env.TFM_PLATFORM == "arm/mps2/an521") {
       device_type = "--fvp-only "
       print("Run test cases only on FVP in tf-m-static.")
     }