nvmet: update smart log with num err log entries

Now that we have error log page implementation update smart log command
handler to provide number of error log entries in the lifetime of the
controller field.

Signed-off-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Christoph Hellwig <hch@lst.de>