ksym_tracer: Fix validation of length of access type

Don't take newline into account, otherwise:

 # echo 'pid_max:-w-' > ksym_trace_filter
 # echo -n 'pid_max:rw-' > ksym_trace_filter
 bash: echo: write error: Invalid argument

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: "K.Prasad" <prasad@linux.vnet.ibm.com>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <4A52E2EB.9070503@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>