cmd/compile: revert change to "bound" in typecheckarraylit

In CL 204617, I intend to make "bound" parameter to have special meaning
in typecheckarraylit, so we can distinguish between type-checks array
literal and slice literal. But we end up with other solution. The CL was
submitted without reverting the "bound" parameter in case of slice
literal.

Technically, it's not harmful, but causes the code harder to read and maintain.

Change-Id: Ia522ccc9a6b8e25d7eaad4aa4957cb4fa18edc60
Reviewed-on: https://go-review.googlesource.com/c/go/+/204618
Run-TryBot: Cuong Manh Le <cuong.manhle.vn@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>

src/cmd/compile/internal/gc/typecheck.go

@@ -2809,7 +2809,7 @@ func typecheckcomplit(n *Node) (res *Node) {
 		n.Right = nil
 
 	case TSLICE:
-		length := typecheckarraylit(t.Elem(), -2, n.List.Slice(), "slice literal")
+		length := typecheckarraylit(t.Elem(), -1, n.List.Slice(), "slice literal")
 		n.Op = OSLICELIT
 		n.Right = nodintconst(length)