FreeBSD 13.1 changes

[Lewis Donzis]

Apparently FreeBSD 13.1 changed the syntax of the CPUSET macros, so DPDK no longer compiles. 

For example, here's one definition on FreeBSD 13.0 and prior: 

   CPU_OR(cpuset_t *dst, cpuset_t *src); 

and here it is in FreeBSD 13.1: 

   CPU_OR(cpuset_t *dst, cpuset_t *src1, cpuset_t *src2); 

I've modified lib/eal/freebsd/include/rte_os.h to handle both old and new versions of FreeBSD. 

I'd like to provide the updated file, if someone would be willing to review and commit, please? 

Thanks, 
lew