[RISCV] Support BSET/BCLR/BINV in hasAllWUsers.

These instructions set, clear, or invert a single bit. If their
users don't use the upper 32 bits, they don't use the upper 32 bits
of their input.

Additionally the second operand BSET/BCLR/BINV is a shift amount
which only uses 6 bits of the source.

Reviewed By: asb

Differential Revision: https://reviews.llvm.org/D137452