eal: fix errno in IPC API
eal: fix errno in IPC API

rte_errno values should not be negative.

Fixes: bacaa2754017 ("eal: add channel for multi-process communication")
Fixes: 783b6e54971d ("eal: add synchronous multi-process communication")

Signed-off-by: Anatoly Burakov <814e00d8f6e4e81b7ccc7e3e5a0bfec0078f0203@intel.com>
Reviewed-by: Jianfeng Tan <4339d9ba3a87a0d192e405945005ff86667f7b0c@intel.com>

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