Remove low-hanging fruit rustfmt::skips in Channel

rustfmt::skips were added recently all over channel.rs in order for formatting
to be enforced for all new code added to the file.

Here we remove a bunch of those skips that aren't necessary because the methods
that are skipped are so short.

Does not include cfg(splicing) code.

Here we just remove the rustfmt skips, in the next commit we'll clean up the
code that rustfmt made too vertical.

Author: valentinewallace