nvme: lightnvm: return ppa completion status

PPAs sent to device is separately acknowledge in a 64bit status
variable. The status is stored in DW0 and DW1 of the completion queue
entry. Store this status inside the nvm_rq for further processing.

This can later be used to implement retry techniques for failed writes
and reads.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Matias Bjørling <m@bjorling.me>
Signed-off-by: Jens Axboe <axboe@fb.com>
diff --git a/include/linux/lightnvm.h b/include/linux/lightnvm.h
index 0ee2c2c..cdcb2cc 100644
--- a/include/linux/lightnvm.h
+++ b/include/linux/lightnvm.h
@@ -242,6 +242,7 @@
 	uint16_t nr_pages;
 	uint16_t flags;
 
+	u64 ppa_status; /* ppa media status */
 	int error;
 };