zram: break the strict dependency from lzo

From the beginning, the zram block device always enabled CRYPTO_LZO,
since lzo-rle is hardcoded as the fallback compression algorithm.  As a
consequence, on systems where another compression algorithm is chosen
(e.g.  CRYPTO_ZSTD), the lzo kernel module becomes unused, while still
having to be built/loaded.

This patch removes the hardcoded lzo-rle dependency and allows the user
to select the default compression algorithm for zram at build time.  The
previous behaviour is kept, as the default algorithm is still lzo-rle.

Link: https://lkml.kernel.org/r/20201207121245.50529-1-rsalvaterra@gmail.com


Signed-off-by: Rui Salvaterra <rsalvaterra@gmail.com>
Suggested-by: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Suggested-by: Minchan Kim <minchan@kernel.org>
Acked-by: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>