netdev-dpdk: Fix possible memory leak configuring VF MAC address. #450

Job	Run time
osx clang --disable-ssl	3m 4s
linux rpm fedora	4m 7s
dpdk gcc	1m 22s
linux deb no dpdk	6m 41s
clang-analyze	17m 55s
linux gcc --disable-ssl	2m 27s
linux clang --disable-ssl	2m 22s
linux gcc c99	2m 23s
linux clang c99	2m 31s
linux gcc test	8m 10s
linux clang address,undefined test	15m 59s
linux gcc test --enable-shared	10m 55s
linux clang test --enable-shared	11m 8s
linux gcc check check-dpdk dpdk	17m 21s
linux clang check check-dpdk dpdk	17m 3s
linux gcc test -ljemalloc	8m 47s
linux clang test -ljemalloc	8m 45s
linux gcc --enable-afxdp	2m 25s
linux clang --enable-afxdp	2m 32s
linux gcc dpdk --enable-shared	3m 49s
linux clang dpdk --enable-shared	3m 44s
linux gcc dpdk-shared	2m 40s
linux clang dpdk-shared	2m 45s
linux gcc dpdk-shared --enable-shared	3m 39s
linux clang dpdk-shared --enable-shared	3m 54s
linux gcc m32 --disable-ssl	2m 34s
linux gcc check-ovsdb-cluster	6m 31s
linux gcc check-kernel -100	8m 49s
linux gcc check-kernel 100-	9m 38s
linux clang address,undefined check-kernel -100	11m 19s
linux clang address,undefined check-kernel 100-	12m 2s
linux gcc check-offloads -100	9m 6s
linux gcc check-offloads 100-	7m 18s
linux gcc dpdk check-system-userspace	10m 52s
linux clang address,undefined dpdk check-system-userspace	14m 5s
linux gcc dpdk check-system-tso	10m 29s
linux gcc dpdk check-afxdp	10m 45s
	4h 39m 56s

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