Use miopen_LIBRARIES and rccl_LIBRARIES directly, when they are valid target (pytorch#80446)

As of [this RCCL PR](ROCm/rccl#570), `${rccl_LIBRARIES}` refers to the actual RCCL library target, not just a symbolic "rccl" string. So starting from the next release, no special treatment of it would be required in PyTorch anymore. This patch checks whether `${RCCL_LIBRARIES}` and `${MIOpen_LIBRARIES}` are already valid, and if they are - is not trying to find them manually.

Pull Request resolved: pytorch#80446
Approved by: https://github.com/pruthvistony, https://github.com/malfet

Author: dmikushin

cmake/public/LoadHIP.cmake

@@ -300,10 +300,18 @@ if(HIP_FOUND)
   find_library(PYTORCH_HIP_HCC_LIBRARIES ${hip_library_name} HINTS ${HIP_PATH}/lib)
   # TODO: miopen_LIBRARIES should return fullpath to the library file,
   # however currently it's just the lib name
-  find_library(PYTORCH_MIOPEN_LIBRARIES ${miopen_LIBRARIES} HINTS ${MIOPEN_PATH}/lib)
+  if(TARGET ${miopen_LIBRARIES})
+    set(PYTORCH_MIOPEN_LIBRARIES ${miopen_LIBRARIES})
+  else()
+    find_library(PYTORCH_MIOPEN_LIBRARIES ${miopen_LIBRARIES} HINTS ${MIOPEN_PATH}/lib)
+  endif()
   # TODO: rccl_LIBRARIES should return fullpath to the library file,
   # however currently it's just the lib name
-  find_library(PYTORCH_RCCL_LIBRARIES ${rccl_LIBRARIES} HINTS ${RCCL_PATH}/lib)
+  if(TARGET ${rccl_LIBRARIES})
+    set(PYTORCH_RCCL_LIBRARIES ${rccl_LIBRARIES})
+  else()
+    find_library(PYTORCH_RCCL_LIBRARIES ${rccl_LIBRARIES} HINTS ${RCCL_PATH}/lib)
+  endif()
   # hiprtc is part of HIP
   find_library(ROCM_HIPRTC_LIB ${hip_library_name} HINTS ${HIP_PATH}/lib)
   # roctx is part of roctracer