[RISCV] Fold (select_cc (setlt X, Y), 0, ne, trueV, falseV) -> (select_cc X, Y, lt...

[RISCV] Fold (select_cc (setlt X, Y), 0, ne, trueV, falseV) -> (select_cc X, Y, lt, trueV, falseV)

A setcc can be created during LegalizeDAG after select_cc has been
created. This combine will enable us to fold these late setccs.

Reviewed By: luismarques

Differential Revision: https://reviews.llvm.org/D98132