Remove non_pawn_material in NNUE::evaluate

Remove non_pawn_material in NNUE::evaluate

After "Use NNUE complexity in search, retune related parameters" commit,
the effect of non-pawn material adjustment has been nearly diminished.
This patch removes pos.non_pawn_material as a simplification, which
passed non-regression tests with both STC and LTC.

Passed non-regression STC:
LLR: 2.95 (-2.94,2.94) <-1.75,0.25>
Total: 75152 W: 20030 L: 19856 D: 35266
Ptnml(0-2): 215, 8281, 20459, 8357, 264
https://tests.stockfishchess.org/tests/view/641ab471db43ab2ba6f7bc58

Passed non-regression LTC:
LLR: 2.94 (-2.94,2.94) <-1.75,0.25>
Total: 193864 W: 51870 L: 51829 D: 90165
Ptnml(0-2): 86, 18968, 58794, 18987, 97
https://tests.stockfishchess.org/tests/view/641b4fe6db43ab2ba6f7db96

closes https://github.com/official-stockfish/Stockfish/pull/4461

Bench: 5020718