[NVPTX] Remove extra ';' outside of a function (NFC)

/llvm-project/llvm/lib/Target/NVPTX/NVPTXISelLowering.cpp:224:2:
error: extra ';' outside of a function is incompatible with C++98 [-Werror,-Wc++98-compat-extra-semi]
};
 ^
1 error generated.

llvm/lib/Target/NVPTX/NVPTXISelLowering.cpp

@@ -221,7 +221,7 @@ getVectorLoweringShape(EVT VectorVT) {
   }
 
   llvm_unreachable("All cases in switch should return.");
-};
+}
 
 /// ComputePTXValueVTs - For the given Type \p Ty, returns the set of primitive
 /// EVTs that compose it.  Unlike ComputeValueVTs, this will break apart vectors