SWDEV-448163 - Fix Doxygen warnings

Change-Id: If72e312461a72920b6a482009c9aef4cf92f2e1b

catch/unit/math/casting_half_float_funcs.cc

@@ -244,4 +244,9 @@ CAST_REF_DEF(__half2float, float, Float16)
 TEST_CASE("Unit_Device___half2float_Accuracy_Positive") {
   float (*ref)(Float16) = __half2float_ref;
   UnaryHalfPrecisionTest(__half2float_kernel, ref, EqValidatorBuilderFactory<float>());
-}
+}
+
+/**
+* End doxygen group MathTest.
+* @}
+*/