Merge branch 'samples-pktgen-allow-to-specify-destination-IP-range'

Daniel T. Lee says:

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samples: pktgen: allow to specify destination IP range

Currently, pktgen script supports specify destination port range.

To further extend the capabilities, this commit allows to specify destination
IP range with CIDR when running pktgen script.

Specifying destination IP range will be useful on various situation such as
testing RSS/RPS with randomizing n-tuple.

This patchset fixes the problem with checking the command result on proc_cmd,
and add feature to allow destination IP range.
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Signed-off-by: David S. Miller <davem@davemloft.net>