[add] utest kernel mutex_tc.c file

examples/utest/testcases/kernel/Kconfig

@@ -31,4 +31,8 @@ config UTEST_SIGNAL_TC
     bool "signal test"
     default n
 
+config UTEST_MUTEX_TC
+    bool "mutex test"
+    default n
+
 endmenu

examples/utest/testcases/kernel/SConscript

@@ -26,6 +26,9 @@ if GetDepend(['UTEST_MESSAGEQUEUE_TC']):
 if GetDepend(['UTEST_SIGNAL_TC']):
     src += ['signal_tc.c']
 
+if GetDepend(['UTEST_MUTEX_TC']):
+    src += ['mutex_tc.c']
+
 CPPPATH = [cwd]
 
 group = DefineGroup('utestcases', src, depend = [], CPPPATH = CPPPATH)