shader_ir: Unify constant buffer offset values

Constant buffer values on the shader IR were using different offsets if
the access direct or indirect. cbuf34 has a non-multiplied offset while
cbuf36 does. On shader decoding this commit multiplies it by four on
cbuf34 queries.

src/video_core/shader/decode/arithmetic.cpp

@@ -25,7 +25,7 @@ u32 ShaderIR::DecodeArithmetic(BasicBlock& bb, const BasicBlock& code, u32 pc) {
         } else if (instr.is_b_gpr) {
             return GetRegister(instr.gpr20);
         } else {
-            return GetConstBuffer(instr.cbuf34.index, instr.cbuf34.offset);
+            return GetConstBuffer(instr.cbuf34.index, instr.cbuf34.GetOffset());
         }
     }();