event/dsw: fix gcc 4.8 false positive warning
event/dsw: fix gcc 4.8 false positive warning

Add redundant stack variable initialization to work around
false-positive warnings in older versions of GCC.

Fixes: 1f2b99e8d9b1 ("event/dsw: improve migration mechanism")

Signed-off-by: Mattias Rönnblom <ba23a026ae54c0c95a377f3421ce76e4585cf9f8@ericsson.com>

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