nvme: fw-download: handle overlapping range errors

nvme: fw-download: handle overlapping range errors

Some NVMe implementations may return an Overlapping Range error if we
attempt to re-send a image range that has already been sent to a device.
We may hit this in a couple scenarios:

 - a prior Firmware Image Download command succeeded, but the success
   response was lost due to unrelated transport issues
 - a download has been cancelled, and is now being re-attempted

In order to handle this, this change adds a --ignore-ovr option to the
fw-download subcommand, which treats the Overlapping Range errors as
non-fatal, allowing the firmware download to proceed with the
non-overlapping portions.

We don't make this the default behaviour, because we cannot guarantee
that the currently-upoloaded portion is what has already been sent to
the device (and the user actually wants to overwrite with new image
data). In those cases, a firmware commit or device reset is required
instead.

Signed-off-by: Jeremy Kerr <jk@codeconstruct.com.au>