Two fixes

- The script will stop running if ${swapf[Poff]} is not set. I've dig into it a bit, and find the offending line:
```
[ ! -z ${swapf[Poff]} ] && [ ! -z "${swapd[devs]}" ] && unset swapf
```
so if ${swapf[Poff]} not set, it will be treated as an error, and preventing the rest of the script from executing. The -x output stops here:
```
+ swapd[devs]='/dev/sde1 '
+ '[' '!' -z ']'
```

- While switching to max_comp_streams, the unit "K" is missing. The ${sys[ram_size]} still remains in the same unit (K), so manage_zram always create a mini zram swap device. Adding the missing K fixes this.