Clean up naming in expr_value()
Clean up naming in expr_value()

Reuse the v1/v2 naming for the operands for the relation case, and call
the relation variable 'rel' instead of 'op'.

Piggy-back removal of the 'res' variable. Just as readable without it.

Indirectly strips some locals.

ulfalizer/Kconfiglib,ulfalizer/Kconfiglib