Fix RemoveWires handling of invalidated non-UInt wires (bp #1949) (#1953)

* Fix RemoveWires handling of invalidated non-UInt wires (#1949)

It would replace them with a validif node with a UIntLiteral which can
lead to type errors.

(cherry picked from commit c7bbb75b

)

# Conflicts:
#	src/main/scala/firrtl/passes/RemoveValidIf.scala
#	src/main/scala/firrtl/transforms/RemoveWires.scala

* Resolve conflicts

Co-authored-by: Jack Koenig <koenig@sifive.com>
Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>