QPR-12140 fix

Author: pcaspers

ql/math/randomnumbers/sobolrsg.cpp

@@ -78795,7 +78795,7 @@ namespace QuantLib {
         } else {
             std::fill(integerSequence_.begin(), integerSequence_.end(), 0.0);
             std::uint_least32_t mask = 1;
-            for (Size index = 0; index < dimensionality_; index++) {
+            for (Size index = 0; index < bits_; index++) {
                 if ((N & mask) != 0U) {
                     for (Size k = 0; k < dimensionality_; k++) {
                         integerSequence_[k] ^= directionIntegers_[k][index];