Pull a patch from kernel git to unbreak dropbear.

Dropbear hangs while reading /proc/timer_list for entropy.  Fixed with
this patch, which should be available in 3.11.
The commit ID from the kernel git repo is:
84a78a6504f5c5394a8e558702e5b54131f01d14
Merge pull request #110 from CMB/timerlist

Pull a patch from kernel git to unbreak dropbear.