sparc64,ftrace: Remove check of obsolete variable function_trace_stop

Nothing sets function_trace_stop to disable function tracing anymore.
Remove the check for it in the arch code.

Link: http://lkml.kernel.org/r/20140703.211820.1674895115102216877.davem@davemloft.net



Cc: David S. Miller <davem@davemloft.net>
OKed-to-go-through-tracing-tree-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>