ftrace: Add cond_resched() to ftrace_graph_set_hash()

In the Linux kernel, the following vulnerability has been resolved:

ftrace: Add cond_resched() to ftrace_graph_set_hash()

When the kernel contains a large number of functions that can be traced,

the loop in ftrace_graph_set_hash() may take a lot of time to execute.

This may trigger the softlockup watchdog.

Add cond_resched() within the loop to allow the kernel to remain

responsive even when processing a large number of functions.

This matches the cond_resched() that is used in other locations of the

code that iterates over all functions that can be traced.