compat-drivers: netlink_callback min_dump_alloc only exists since 3.1

Upstream commit db0e9cad45c9199cf14ae5b9d78d8dd6697d7860

The netlink callback min_dump_alloc only exists on kernel
3.1 so only enable using it for those kernels. If you're
on an older 64-bit kernel and want this functionality of
resizing the data sent to userspace for a wiphy dump then
you better upgrade.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Luis R. Rodriguez <mcgrof@do-not-panic.com>