Fixing compilation error when re-exporting module with same name as a Rust package.

[pellico]

Added self:: when referencing submodule to avoid ambiguity fix issue https://github.com/rust-embedded/svd2rust/issues/657

[rust-highfive]

Thanks for the pull request, and welcome! The Rust team is excited to review your changes, and you should hear from @burrbull (or someone else) soon.

Please see the contribution instructions for more information.

[burrbull]

LGTM. bors r+

[bors[bot]]

:-1: Rejected by too few approved reviews

[burrbull]

bors retry

[bors[bot]]

Build succeeded:

• CI
• Rustfmt