path/filepath: remove extra Clean call in EvalSymlinks on Windows

path/filepath: remove extra Clean call in EvalSymlinks on Windows

EvalSymlinks calls Clean twice, one in walkSymlinks and another in
toNorm. The later is not necessary, as toNorm is only called by
EvalSymlinks and just after walkSymlinks cleans the path without any
path manipulation in between.

Change-Id: Ibdb782c7eed59468f0ebb913e98d2a7db0df010d
Reviewed-on: https://go-review.googlesource.com/c/go/+/454615
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Bryan Mills <bcmills@google.com>
Reviewed-by: Damien Neil <dneil@google.com>
Run-TryBot: Quim Muntal <quimmuntal@gmail.com>