net/sfc: correct RSS hash availability condition
net/sfc: correct RSS hash availability condition

RSS hash is computed by hardware if corresponding Rx filter (for
example, default Rx filters) has RSS flag set which is set if
the number of RSS channels is greater than zero.

Fixes: 4ec1fc3ba881 ("net/sfc: add basic stubs for RSS support on driver attach")
Cc: stable@dpdk.org

Signed-off-by: Andrew Rybchenko <ac94ab2a8fe9a9a087f6e24dcbc16626b52c07e8@solarflare.com>
Reviewed-by: Andy Moreton <adbee5d9b6a6a553b71b14302d03837591e26c9d@solarflare.com>

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