Use a string to replace null value of PROFILE param

Jenkins does not allow null value for params.
A string is used to indicate the null value of PROFILE param.

Change-Id: I9d23a0d6dd206d8890d3ffb70023fe4b16e8cc09
Signed-off-by: Xinyu Zhang <xinyu.zhang@arm.com>
diff --git a/tfm_ci_pylib/tfm_build_manager.py b/tfm_ci_pylib/tfm_build_manager.py
index b699b54..a05edb1 100644
--- a/tfm_ci_pylib/tfm_build_manager.py
+++ b/tfm_ci_pylib/tfm_build_manager.py
@@ -100,7 +100,7 @@
             "OTP={}",
             "BL2={}",
             "NS={}",
-            "PROFILE={} "
+            "PROFILE={}"
         ]
         print(
             "\n".join(argument_list)
@@ -116,7 +116,7 @@
                 config_details.with_otp,
                 config_details.with_bl2,
                 config_details.with_ns,
-                config_details.profile
+                "N.A" if not config_details.profile else config_details.profile
             )
             .strip()
         )
@@ -371,7 +371,7 @@
                             "with_otp": i.with_otp,
                             "with_bl2": i.with_bl2,
                             "with_ns": i.with_ns,
-                            "profile": i.profile}
+                            "profile": "" if i.profile=="N.A" else i.profile}
         build_cfg["config_template"] %= overwrite_params
         return build_cfg