trace-cmd: Zero out item_arg in process_paran
trace-cmd: Zero out item_arg in process_paran

The print arg gets its fields processed the first time they are used.
If the field is not initialized to zero, this will cause it to
use an uninitialized field and crash.

Signed-off-by: Steven Rostedt <43232e92d70cc7aa53504ad0397085ee47bad87f@goodmis.org>

bigzz/trace-cmd,bigzz/trace-cmd