service: fix build with gcc 4.9
service: fix build with gcc 4.9

Some compilers detect this error:

    error: ‘ids[0]’ may be used uninitialized in this function
    ret = rte_service_map_lcore_set(i, ids[lcore_iter], 1);

It can be reproduced very easily on Fedora 21 with
gcc-4.9.2-6.fc21.x86_64.

Fixes: 21698354c832 ("service: introduce service cores concept")
Cc: stable@dpdk.org

Signed-off-by: Yi Yang <1e26879e47df1049eb9cc7a5ee70fc952788cc72@intel.com>
Acked-by: Harry van Haaren <b9ad04ed670c22cfa7f5f9ab17e311ca85d11a76@intel.com>

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