nvme: allow passthru cmd error logging

Commit d7ac8dca ("nvme: quiet user passthrough command errors")
disabled error logging for user passthrough commands.  This commit
adds the ability to opt-in to passthrough admin error logging. IO
commands initiated as passthrough will always be logged.

The logging output for passthrough commands (Admin and IO) has been
changed to include CDWXX fields.

nvme0n1: Read(0x2), LBA Out of Range (sct 0x0 / sc 0x80) DNR cdw10=0x0 cdw11=0x1
        cdw12=0x70000 cdw13=0x0 cdw14=0x0 cdw15=0x0

Add a helper function nvme_log_err_passthru() which allows us to log
error for passthru commands by decoding cdw10-cdw15 values of nvme
command.

Add a new sysfs attr passthru_err_log_enabled that allows user to conditionally
enable passthrough command logging for either passthrough Admin commands sent to
the controller or passthrough IO commands sent to a namespace.

By default, passthrough error logging is disabled.

To enable passthrough admin error logging:
        echo 1 > /sys/class/nvme/nvme0/passthru_err_log_enabled

To disable passthrough admin error logging:
        echo 0 > /sys/class/nvme/nvme0/passthru_err_log_enabled

To enable passthrough io error logging:
        echo 1 > /sys/class/nvme/nvme0/nvme0n1/passthru_err_log_enabled

To disable passthrough io error logging:
        echo 0 > /sys/class/nvme/nvme0/nvme0n1/passthru_err_log_enabled

Signed-off-by: Alan Adamson <alan.adamson@oracle.com>
Signed-off-by: Chaitanya Kulkarni <kch@nvidia.com>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Keith Busch <kbusch@kernel.org>