lightnvm: initialize ppa_addr in dev_to_generic_addr()

BugLink: http://bugs.launchpad.net/bugs/1715430

commit 5389a1df upstream.

The ->reserved bit is not initialized when allocated on stack.
This may lead targets to misinterpret the PPA as cached.
Signed-off-by: Javier González <javier@cnexlabs.com>
Signed-off-by: Matias Bjørling <m@bjorling.me>
Signed-off-by: Jens Axboe <axboe@fb.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

include/linux/lightnvm.h

@@ -373,6 +373,7 @@ static inline struct ppa_addr dev_to_generic_addr(struct nvm_dev *dev,
 {
 	struct ppa_addr l;
 
+	l.ppa = 0;
 	/*
 	 * (r.ppa << X offset) & X len bitmask. X eq. blk, pg, etc.
 	 */