eventdev: fix build for clang 4
eventdev: fix build for clang 4

build error:
.../lib/librte_eventdev/rte_eventdev.c:371:6:
error: logical not is only applied to the left hand side of this
bitwise operator [-Werror,-Wlogical-not-parentheses]
  if (!dev_conf->event_dev_cfg & RTE_EVENT_DEV_CFG_PER_DEQUEUE_TIMEOUT)
      ^
Added parentheses after the '!' to evaluate the bitwise operator first.

Signed-off-by: Ferruh Yigit <ba8734c3c506d2e3557bd4ac8fdaccd25bdb9aa7@intel.com>

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