cmake hip-rocclr as default build,change HIP_PLATFORM to amd|nvidia

Change-Id: I59d2e15b297b6ca2d5eee1a6dee642bdb01a3839


[ROCm/clr commit: 8717a78bf7]

projects/clr/hipamd/tests/src/kernel/hipExtLaunchKernelGGL.cpp

@@ -19,7 +19,7 @@ THE SOFTWARE.
 // Test the Grid_Launch syntax.
 
 /* HIT_START
- * BUILD: %t %s ../test_common.cpp EXCLUDE_HIP_PLATFORM nvcc
+ * BUILD: %t %s ../test_common.cpp EXCLUDE_HIP_PLATFORM nvidia
  * TEST: %t
  * HIT_END
  */