Update Eigen to commit:6156797016164b87b3e360e02d0e4107f7f66fbc

CHANGELOG
=========
615679701 - Revert "Add template to specify QR permutation index type, Fix ColPivHouseholderQR Lapacke bindings"
be7791e09 - Add template to specify QR permutation index type, Fix ColPivHouseholderQR Lapacke bindings
9463fc95f - change insert strategy
c54785b07 - Fix error: unused parameter '\''tmp'\'' [-Werror,-Wunused-parameter] on clang/32-bit arm
f47472603 - Add missing header for GPU tests.
81172cbdc - Overhaul Sparse Core
925518189 - Modified spbenchsolver help message because it could be misunderstood
d20fe21ae - Improve performance for Power10 MMA bfloat16 GEMM
fe7f52778 - Fix guard macros for emulated FP16 operators on GPU
b8422c99c - Update file jacobisvd.cpp
262194f12 - Fix a bunch of minor build and test issues.

PiperOrigin-RevId: 501682808
Change-Id: If89a17cd8160863cb158c4cd4f0814260bd5857d
25 files changed