net: mvneta: Use on_each_cpu when possible

Instead of using a for_each_* loop in which we just call the
smp_call_function_single macro, it is more simple to directly use the
on_each_cpu macro. Moreover, this macro ensures that the calls will be
done all at once.

Suggested-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
Signed-off-by: David S. Miller <davem@davemloft.net>