Clean up SkFontMgr_fuchsia.cpp after FIDL API change

This cleans up some changes made in:
https://skia-review.googlesource.com/c/179994

Bug: skia:
Change-Id: I813f44578fd6dcd0da8a3ec3a877f307c6e36093
Reviewed-on: https://skia-review.googlesource.com/c/196504
Reviewed-by: Mike Klein <mtklein@google.com>
Commit-Queue: Mike Klein <mtklein@google.com>
1 file changed