M2351: Translate target name to platform name

Translate target name 'NU_PFM_M2351'+SUFFIX to platform name 'NUMAKER_PFM_M2351'
for the NuMaker-PFM-M2351 board:

1.  Online database has limit of max 20 chars on target name, so we cannot follow
    the naming rule 'NUMAKER_PFM_M2351'+SUFFIX for this board.
2.  The registered platform name 'NUMAKER_PFM_M2351' in mbed-os-tools keeps
    unchanged for compatibility.

Author: ccli8

tools/test_api.py

@@ -2272,7 +2272,17 @@ def build_tests(tests, base_source_paths, build_path, target, toolchain_name,
 
 def test_spec_from_test_builds(test_builds):
     for build in test_builds:
-        if Target.get_target(test_builds[build]['platform']).is_PSA_non_secure_target:
+        if test_builds[build]['platform'][:12] == 'NU_PFM_M2351':
+            # Translate target name 'NU_PFM_M2351'+SUFFIX to platform name
+            # 'NUMAKER_PFM_M2351' for the NuMaker-PFM-M2351 board:
+            #
+            # 1. Online database has limit of max 20 chars on target name,
+            #    so we cannot follow the naming rule 'NUMAKER_PFM_M2351'+
+            #    SUFFIX for this board.
+            # 2. The registered platform name 'NUMAKER_PFM_M2351' in mbed-os-tools
+            #    keeps unchanged for compatibility.
+            test_builds[build]['platform'] = 'NUMAKER_PFM_M2351'
+        elif Target.get_target(test_builds[build]['platform']).is_PSA_non_secure_target:
             if test_builds[build]['platform'].endswith('_NS'):
                 test_builds[build]['platform'] = test_builds[build]['platform'][:-3]
             if test_builds[build]['platform'].endswith('_PSA'):