examples/l3fwd-power: fix build with gcc 4
examples/l3fwd-power: fix build with gcc 4

error: ‘for’ loop initial declarations are only allowed in C99 mode

Fixes: 609e79841fcf ("examples/l3fwd-power: add telemetry mode")

Signed-off-by: Thomas Monjalon <5f50a84c1fa3bcff146405017f36aec1a10a9e38@monjalon.net>

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