Do some light multitap cleanup

After seeing the regressions from multitap I took a quick look at the
code, and there's quite a bit of cleanup needed.

This fixes the initial really obvious stuff, a useless copy and a
duplicate in_keystate that can cause compilation issues, along with
bringing styling closer to the pcsx standard so it's a bit more readable.

The multitap changeset also seems to have been done with an editor that
mangled line endings, I'll address that in a followup commit.