CLEANUP: peers: Remove unused static function `free_dcache_tx`

The function was added in commit 6c39198b575444466ddfc5368e481d2a7cf8111d,
but was also used within a single function `free_dcache` which was unused
itself.

see issue #301
see commit 10ce0c2f31ba06e52edfb52176dc47986314321b which removed
`free_dcache`
1 file changed