zramctl: mark --reset mutually exclusive with --algorithm and --streams

Reset is setting algorithm to lz4 and streams to 1.

Signed-off-by: Sami Kerola <kerolasa@iki.fi>
zramctl: fail status printout when device does not exist

Earlier.

$ zramctl zram313 ; echo $?
0

Now.

$ zramctl zram313 ; echo $?
zramctl: zram313: no such device
1

Signed-off-by: Sami Kerola <kerolasa@iki.fi>
zramctl: improve error message

Signed-off-by: Sami Kerola <kerolasa@iki.fi>
zramctl: fix mount point printout

See sample belo how a device mount point was printed without and with
full <device> path.  This change adds the mount point markup to the short
device name printout.

$ zramctl zram3
NAME  ALGORITHM DISKSIZE DATA COMPR TOTAL STREAMS MOUNTPOINT
zram3 lz4             1M   4K   62B    4K       1

$ zramctl /dev/zram3
NAME       ALGORITHM DISKSIZE DATA COMPR TOTAL STREAMS MOUNTPOINT
/dev/zram3 lz4             1M   4K   62B    4K       1 [SWAP]

Signed-off-by: Sami Kerola <kerolasa@iki.fi>
zramctl: add bash completion script

Signed-off-by: Sami Kerola <kerolasa@iki.fi>