nvme: fix miss command type check

In the function nvme_passthru_end(), only the value of the command
opcode is checked, without checking the command type (IO command or
Admin command). When we send a Dataset Management command (The opcode
of the Dataset Management command is the same as the Set Feature
command), kernel thinks it is a set feature command, then sets the
controller's keep alive interval, and calls nvme_keep_alive_work().

Signed-off-by: min15.li <min15.li@samsung.com>
Reviewed-by: Kanchan Joshi <joshi.k@samsung.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Keith Busch <kbusch@kernel.org>