devlink: display elapsed time during flash update

devlink: display elapsed time during flash update

For some devices, updating the flash can take significant time during
operations where no status can meaningfully be reported. This can be
somewhat confusing to a user who sees devlink appear to hang on the
terminal waiting for the device to update.

Recent changes to the kernel interface allow such long running commands
to provide a timeout value indicating some upper bound on how long the
relevant action could take.

Provide a ticking counter of the time elapsed since the previous status
message in order to make it clear that the program is not simply stuck.

Display this message whenever the status message from the kernel
indicates a timeout value. Additionally also display the message if
we've received no status for more than couple of seconds. If we elapse
more than the timeout provided by the status message, replace the
timeout display with "timeout reached".

Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Signed-off-by: David Ahern <dsahern@gmail.com>