NVMe: Add definitions for format command

The SCSI emulation has the ability to send format commands, so we need
to add the definition of the command.  Also add a missing error code.

Signed-off-by: Vishal Verma <vishal.l.verma@intel.com>
Signed-off-by: Matthew Wilcox <matthew.r.wilcox@intel.com>

diff --cc drivers/block/nvme-core.c
Simple merge

diff --cc include/linux/nvme.h
Simple merge