crypto: deadcode structs from 'comp' removal

Ard's recent series of patches removing 'comp' implementations
left behind a bunch of trivial structs, remove them.

These are:
  crypto842_ctx - commit 2d985ff0 ("crypto: 842 - drop obsolete 'comp'
implementation")
  lz4_ctx       - commit 33335afe ("crypto: lz4 - drop obsolete 'comp'
implementation")
  lz4hc_ctx     - commit dbae9655 ("crypto: lz4hc - drop obsolete
'comp' implementation")
  lzo_ctx       - commit a3e43a25 ("crypto: lzo - drop obsolete
'comp' implementation")
  lzorle_ctx    - commit d32da55c ("crypto: lzo-rle - drop obsolete
'comp' implementation")

Signed-off-by: Dr. David Alan Gilbert <linux@treblig.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>