[LTP] [PATCH v4 2/4] zram/zram_lib.sh: adapt the situation that zram device is being used

[Petr Vorel]

> If zram-generator package is installed and works, then we can not remove zram module
> because zram swap is being used. This case needs a clean zram environment, change this
> test by using hot_add/hot_remove interface[1]. So even zram device is being used, we
> still can add zram device and remove them in cleanup.
BTW this also helped to run zram01.sh simultaneously, which is nice. Thank you.

Kind regards,
Petr