[AMDGPU] Fix Windows build

A trivial fix, 64 bit constant is 1ull, not 1ul on Windows.
Fixed build broken by c0d7a8b.

Change-Id: Ib47687edaf80848d71883d655d3bd3ed9505617c

Author: rampitec

llvm/lib/Target/AMDGPU/MCTargetDesc/SIMCCodeEmitter.cpp

@@ -306,7 +306,7 @@ void SIMCCodeEmitter::encodeInstruction(const MCInst &MI, raw_ostream &OS,
     // unused op_sel_hi bits if corresponding operands do not exist.
     // accvgpr_read/write are different, however. These are VOP3P, MAI, have
     // src0, but do not use op_sel.
-    Encoding |= (1ul << 14) | (1ul << 59) | (1ul << 60);
+    Encoding |= (1ull << 14) | (1ull << 59) | (1ull << 60);
     break;
   default:
     break;