zram-swap: default to lzo instead of lzo-rle compression

zram-swap: default to lzo instead of lzo-rle compression

On devices with small amounts of RAM, zram-swap fails to initialise due to the
default compression algorithm (lzo-rle). Startup example on an AirGrid M2, with
32 MiB of RAM:

root@airgrid:/etc/config# /etc/init.d/zram start
zram_start: activating '/dev/zram0' for swapping (13 MegaBytes)
zram_reset: enforcing defaults via /sys/block/zram0/reset
sh: write error: Out of memory
mkswap: image is too small
swapon: /dev/zram0: Invalid argument
root@airgrid:/etc/config#

Fix this by defaulting to traditional lzo, which works fine and is always
available.

Signed-off-by: Rui Salvaterra <rsalvaterra@gmail.com>