uprobes: Fix return value in error handling path

uprobes: Fix return value in error handling path

When wrong argument is passed into uprobe_events it does not return
an error:

[root@jovi tracing]# echo 'p:myprobe /bin/bash' > uprobe_events
[root@jovi tracing]#

The proper response is:

[root@jovi tracing]# echo 'p:myprobe /bin/bash' > uprobe_events
-bash: echo: write error: Invalid argument

Link: http://lkml.kernel.org/r/51B964FF.5000106@huawei.com
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: <srikar@linux.vnet.ibm.com>
Cc: stable@vger.kernel.org # 3.5+
Signed-off-by: zhangwei(Jovi) <jovi.zhangwei@huawei.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>