Fix generation of variable location descriptor for llvm.dbg.declare

For support llvm.declare - it is necessary to make the correct
sequence to access the memory location. In base implementation
for llvm.declare generates sequence
```
	0: DW_OP_breg[x]
	1: DW_OP_const1u
	2: DW_OP_const1u
	3: DW_OP_INTEL_push_bit_piece_stack
```
DW_OP_breg[x] - was generated by method addRegisterLoc. But in
intel DWARF extensions - Item #3, transforms the original
"register location" defined by Item #0 to a "memory location".
And this sequence becomes incorrect, because DW_OP_breg is
addressing operation, which pushed on stack  contents of a
register(but here expecting register location).

Here operations DW_OP_breg[x] is replaced for DW_OP_reg[x],
that returns register location for reg.
Sequence for llvm.declare after current change will be:
```
        0: DW_OP_reg[x]
        1: DW_OP_const1u
        2: DW_OP_const1u
        3: DW_OP_INTEL_push_bit_piece_stack
```

Author: igorban-intel

IGC/DebugInfo/DwarfCompileUnit.cpp

@@ -486,10 +486,7 @@ void CompileUnit::addSourceLine(DIE* Die, DIType* Ty)
 
 void CompileUnit::addRegisterLoc(IGC::DIEBlock* TheDie, unsigned DWReg, int64_t Offset, const llvm::Instruction* dbgInst)
 {
-    if (isa<llvm::DbgDeclareInst>(dbgInst))
-        addRegisterOffset(TheDie, DWReg, Offset);
-    else
-        addRegisterOp(TheDie, DWReg);
+    addRegisterOp(TheDie, DWReg);
 }
 
 /// addRegisterOp - Add register operand.