net/ice: add Rx flex descriptor definition
net/ice: add Rx flex descriptor definition

The Rx flex descriptor has 16B and 32B size, with different
field definitions compared to legacy type.

Signed-off-by: Haiyue Wang <037d5f2d0d83548aebdad8ba0c69c0b30ec44c86@intel.com>
Reviewed-by: Xiaolong Ye <c7d6fc2f7e22da80deb234d523238b510a8c0f08@intel.com>
Acked-by: Qi Zhang <9e9e58ffa71a29bb7b87766b362515be648fcbe0@intel.com>

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