Support BFloat16 in exir

Differential Revision: D82129165

Pull Request resolved: pytorch#14164

Author: manuelcandales

exir/dialects/edge/dtype/supported.py

@@ -23,6 +23,7 @@
     torch.int32: "Int",
     torch.int64: "Long",
     torch.float16: "Half",
+    torch.bfloat16: "BFloat16",
     torch.float: "Float",
     torch.double: "Double",
     torch.uint16: "UInt16",