ipc: do not unregister action if IPC unsupported
ipc: do not unregister action if IPC unsupported

Currently, unregister will be attempted even if IPC wasn't
supported in the first place. It is harmless, but for
consistency reasons, update the unregister API call to
exit early when IPC is not supported.

Signed-off-by: Anatoly Burakov <814e00d8f6e4e81b7ccc7e3e5a0bfec0078f0203@intel.com>

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