northd: Remove unnecessary pointer checks. #1439

Job	Run time
linux rpm fedora	6m 50s
osx clang --disable-ssl	2m 31s
Prepare container	3m 38s
linux gcc --disable-ssl	2m 39s
linux clang --disable-ssl	2m 38s
linux gcc test -300	9m 24s
linux gcc test 301-600	6m 22s
linux gcc test 601- unstable	6m 37s
linux clang test sanitizers -300	12m 49s
linux clang test sanitizers 301-600	9m 4s
linux clang test sanitizers 601- unstable	11m 9s
linux gcc test -ljemalloc -300	9m 37s
linux gcc test -ljemalloc 301-600	6m 32s
linux gcc test -ljemalloc 601- unstable	6m 42s
linux gcc system-test-dpdk dpdk -100	16m 53s
linux gcc system-test-dpdk dpdk 101- unstable	14m 10s
linux gcc system-test-userspace -100	15m 40s
linux gcc system-test-userspace 101- unstable	13m 12s
linux gcc system-test -100	18m 23s
linux gcc system-test 101- unstable	16m 55s
linux clang system-test sanitizers -100	20m 17s
linux clang system-test sanitizers 101- unstable	18m 28s
linux x86 gcc --disable-ssl	2m 37s
	3h 53m 7s

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