change stop condition to avoid infinite loops

change stop condition to avoid infinite loops

In net/net.c there is a while (1) that only exits if there is a stop
condition and more then 10 packages or if there is no package received.

If GRUB is idle and enter in this loop, the only condition to leave is
if it doesn't have incoming packages. In a network with heavy traffic
this never happens.

Origin: upstream, http://git.savannah.gnu.org/gitweb/?p=grub.git;a=commitdiff;h=d99d2f84166b0f60673d5c0714605a153946c0fc
Bug-Ubuntu: https://bugs.launchpad.net/bugs/1314134
Last-Update: 2014-04-29

Patch-Name: net-receive-packets-yield.patch