cmd/compile: add required CONVIFACE nodes when translating OFUNCINST node

cmd/compile: add required CONVIFACE nodes when translating OFUNCINST node

In CL 349614. we removed the early transformation code that
was needed to create the implicit CONVIFACE nodes.

Because the transformCall function is not called when translating OFUNCINST.
So we add in needed CONVIFACE nodes via typecheckaste().

Fixes #48598

Change-Id: If9dc7040cdc38ef2e52fdbb08c840095651426f2
Reviewed-on: https://go-review.googlesource.com/c/go/+/351856
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Reviewed-by: Dan Scales <danscales@google.com>
Trust: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Trust: Dan Scales <danscales@google.com>
Run-TryBot: Cuong Manh Le <cuong.manhle.vn@gmail.com>
TryBot-Result: Go Bot <gobot@golang.org>