nfp: don't assume RSS and IRQ moderation are always enabled

Even if capability for RSS and IRQ moderation are present we may
have not initialized them for control vNIC.  Depend on selected
features mask (ctrl) rather than capabilities (cap) to determine
which features should be enabled.

Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Simon Horman <simon.horman@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>