[GPU] Change texture address local X offsetting back to addition

More likely to be emitted as an immediate load/store offset in host
hardware shaders.

src/xenia/gpu/shaders/resolve.xesli

@@ -196,6 +196,10 @@ uint XeResolveEdramPixelStrideInts(XeResolveInfo resolve_info) {
   // XOR to apply to the byte address to flip the bits corresponding to the
   // given X coordinate bits within the macro tile width, or with resolution
   // scaling, within XeniaTextureResolutionScaledGroupElements.x.
+  // Addition is recommended instead of XOR if the bits are known to be 0 in the
+  // original address, so the host GPU driver can optimize it into a constant
+  // store offset if available in the host hardware shader instruction set
+  // architecture.
   uint XeResolveLocalXAddressXor(const uint x,
                                  const uint bytes_per_element_log2) {
     #ifdef XE_RESOLVE_RESOLUTION_SCALED