[amdgpu] Drop multiple calls to hsa_init

[JonChesterfield]

Summary

Revert likely unintentional part of 4075a811ad99b7

[jhuber6]

Seems HSA is already initialized by the RTLDeviceInfoTy pointer, so this is definitely redundant.

[saiislam]

I think we can not remove this initialization.

Are the following failing tests passing after applying this patch?
https://lab.llvm.org/buildbot/#/builders/193/builds/15846

openmp/libomptarget/plugins/amdgpu/src/rtl.cpp

 
 int64_t __tgt_rtl_init_requires(int64_t RequiresFlags) {
   DP("Init requires flags to %ld\n", RequiresFlags);
   DeviceInfo().RequiresFlags = RequiresFlags;
   return RequiresFlags;
 }
 
 int32_t __tgt_rtl_init_device(int DeviceId) {
-  hsa_status_t Err = hsa_init();
-  if (Err != HSA_STATUS_SUCCESS) {
-    DP("HSA Initialization Failed.\n");
-    return HSA_STATUS_ERROR;
-  }
+  hsa_status_t Err;
+
   // this is per device id init
   DP("Initialize the device id: %d\n", DeviceId);
 
   hsa_agent_t Agent = DeviceInfo().HSAAgents[DeviceId];
 
   // Get number of Compute Unit
   uint32_t ComputeUnits = 0;
   Err = hsa_agent_get_info(