net/ice: fix default RSS key generation

net/ice: fix default RSS key generation

In original implementation, device reconfiguration will generate
a new default RSS key if there is no one from user, it is unexpected
when updating a completely unrelated configuration.

This patch makes default RSS key unchanged, during the lifetime of the
DPDK application even if there are multiple reconfigurations.

Fixes: 50370662b727 ("net/ice: support device and queue ops")
Cc: stable@dpdk.org
Signed-off-by: Dapeng Yu <dapengx.yu@intel.com>
Acked-by: Qi Zhang <qi.z.zhang@intel.com>