BpfHandler - eliminate mutex

since it doesn't actually work (this runs in netd, but is meant
to protect against system server modifications)

Test: TreeHugger
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: I87f268f1a68c559b19caa4d625cb9eb8395c91e2

netd/BpfHandlerTest.cpp

@@ -53,7 +53,6 @@ class BpfHandlerTest : public ::testing::Test {
     BpfMap<uint32_t, uint8_t> mFakeUidPermissionMap;
 
     void SetUp() {
-        std::lock_guard guard(mBh.mMutex);
         ASSERT_EQ(0, setrlimitForTest());
 
         mFakeCookieTagMap.resetMap(BPF_MAP_TYPE_HASH, TEST_MAP_SIZE);