nvme: trace all async notice events

This patch removes the tracing of the NVMe Async events out of the
switch so that it can trace all the events including the ones which
are not handled in the nvme_handle_aen_notice(). The events which
are not handled in the nvme_handle_aen_notice() such as
NVME_AER_NOTICE_DISC_CHANGED corresponding event identifier needs
to be added in the drivers/nvme/host/trace.h so that it can stringify
the AER .

Signed-off-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>