lightnvm: normalize geometry nomenclature

Normalize nomenclature for naming channels, luns, chunks, planes and
sectors as well as derivations in order to improve readability.

Signed-off-by: Javier González <javier@cnexlabs.com>
Signed-off-by: Matias Bjørling <mb@lightnvm.io>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/drivers/lightnvm/pblk-core.c b/drivers/lightnvm/pblk-core.c
index 52c0c3e..64c87dd 100644
--- a/drivers/lightnvm/pblk-core.c
+++ b/drivers/lightnvm/pblk-core.c
@@ -1742,10 +1742,10 @@
 	struct nvm_tgt_dev *dev = pblk->dev;
 	struct nvm_geo *geo = &dev->geo;
 	struct pblk_lun *rlun;
-	int nr_luns = geo->all_luns;
+	int num_lun = geo->all_luns;
 	int bit = -1;
 
-	while ((bit = find_next_bit(lun_bitmap, nr_luns, bit + 1)) < nr_luns) {
+	while ((bit = find_next_bit(lun_bitmap, num_lun, bit + 1)) < num_lun) {
 		rlun = &pblk->luns[bit];
 		up(&rlun->wr_sem);
 	}