Unlike getPointer() with just returns the raw pointer, GetPointerToData() derefs the buffer data for DescriptorSets.

Test: dEQP-VK.spirv_assembly.instruction.compute.opcopymemory.struct
Change-Id: I5d8d6139952673a2680f9e05f2f64785198b0797
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/31110Tested-by: Ben Clayton <bclayton@google.com>
Kokoro-Presubmit: kokoro <noreply+kokoro@google.com>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>
Reviewed-by: Chris Forbes <chrisforbes@google.com>