lightnvm: support multiple ppas in nvm_erase_ppa

Sometimes a user want to erase multiple PPAs at the same time. Extend
nvm_erase_ppa to take multiple ppas and number of ppas to be erased.

Signed-off-by: Matias Bjørling <m@bjorling.me>
Signed-off-by: Jens Axboe <axboe@fb.com>
diff --git a/drivers/lightnvm/gennvm.c b/drivers/lightnvm/gennvm.c
index 12ddcaa..262da6d 100644
--- a/drivers/lightnvm/gennvm.c
+++ b/drivers/lightnvm/gennvm.c
@@ -396,7 +396,7 @@
 {
 	struct ppa_addr addr = block_to_ppa(dev, blk);
 
-	return nvm_erase_ppa(dev, addr);
+	return nvm_erase_ppa(dev, &addr, 1);
 }
 
 static struct nvm_lun *gennvm_get_lun(struct nvm_dev *dev, int lunid)