Remove PvNode template from reduction

Remove PvNode template from reduction

This functional simplification removes the PvNode reduction and adjusts
the ttPv lmr condition accordingly. Their definitions only differ by the
inclusions of ttPv. Aside from this, shallow move pruning definition
will be the only other functional difference, but this does not seem to
matter too much.

STC:
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 58908 W: 12980 L: 12932 D: 32996
http://tests.stockfishchess.org/tests/view/5cd1aaaa0ebc5925cf046c6a

LTC:
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 20351 W: 3521 L: 3399 D: 13431
http://tests.stockfishchess.org/tests/view/5cd23fa70ebc5925cf047cd2

Bench: 3687854