ethdev: check device promiscuous state
ethdev: check device promiscuous state

The promiscuous enable and disable functions now check the
promiscuous state of the device before checking if the dev_ops
function exists for the device.

This change is necessary to allow sample applications run on
virtual PMDs, as previously -ENOTSUP returned when the promiscuous
enable function was called. This caused the sample application to
fail unnecessarily.

Signed-off-by: Ciara Power <2dd8f648091a527a3f34edd30b226be01da76a0e@intel.com>
Reviewed-by: Ferruh Yigit <ba8734c3c506d2e3557bd4ac8fdaccd25bdb9aa7@intel.com>
Reviewed-by: Andrew Rybchenko <ac94ab2a8fe9a9a087f6e24dcbc16626b52c07e8@solarflare.com>

john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk