[request for stable inclusion] net: neighbour: prohibit negative value for unres_qlen_bytes parameter

Hi Shan Wei or David,

ce46cc64d47a8afaf13c300b09a7f9c29f4979b6
net: neighbour: prohibit negative value for unres_qlen_bytes parameter

This looks applicable to stable-3.4, I can reproduce it on this 3.4 kernel.
It fixes a type overflow when setting unres_qlen. I try to reproduce, and
then this patch works well. But git am or patch -p1 failed, because a
previous patch [commit 9a6308d74ed (neighbour: Stop using NLA_PUT*().)]
change the NLA_PUT_U32 to nla_put_u32. With some modifies, it was built
successful for me. What do you think?

stable-3.0 and stable-3.2 are free from this bug. And the bug was fixed in
3.8; The commit got its way into mainline in 3.8 cycle.

Thanks!
Wang Weidong