net: optimize ethernet address functions

net: optimize ethernet address functions

* rte_is_broadcast_ether_addr():
Use binary logic instead of comparisons and boolean logic, thus reducing
the number of branches.
It now resembles rte_is_zero_ether_addr().

* rte_ether_addr_copy():
The source code modifications were discussed on the mailing list:
http://mails.dpdk.org/archives/dev/2020-June/171584.html
Remove obsolete ICC-specific code and related comment.
Restrict pointer aliasing (suggested by Jerin Jacob).
Remove superfluous "Fast" from function description headline; all DPDK
data plane functions are supposed to be fast.

Signed-off-by: Morten Brørup <mb@smartsharesystems.com>
Acked-by: Olivier Matz <olivier.matz@6wind.com>