Whether there is a lack of consideration for multiple planes

[bianyu91]

When I read the following code snippet of do_gc() function in bbssd/ftl.c， I‘m wondering why the multi-plane scenario is not taken into count.

`
/* copy back valid data */
for (ch = 0; ch < spp->nchs; ch++) {
for (lun = 0; lun < spp->luns_per_ch; lun++){

        ppa.g.ch = ch;
        ppa.g.lun = lun;
        ppa.g.pl = 0;

....
}
`