tf-sync-github-repos: Update URLs of rust-spmc crates mirrors

We have changed our minds about the Github organization to use for
these mirrors. This affects the URL of the mirrors.

Change-Id: I93dee6341d6234b9d4c71601e38b15fbab094556
Signed-off-by: Sandrine Afsa <sandrine.afsa@arm.com>
1 file changed