lightnvm: initialize ppa_addr in dev_to_generic_addr()

lightnvm: initialize ppa_addr in dev_to_generic_addr()

BugLink: http://bugs.launchpad.net/bugs/1715430
commit 5389a1dfb39786df08d4f6a482bd2734b1b50e33 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>