ring-buffer: remove type parameter from rb_reserve_next_event

The rb_reserve_next_event is only called for the data type (type = 0).
There is no reason to pass in the type to the function.

Before:
   text    data     bss     dec     hex filename
  16554      24      12   16590    40ce kernel/trace/ring_buffer.o

After:
   text    data     bss     dec     hex filename
  16538      24      12   16574    40be kernel/trace/ring_buffer.o

[ Impact: cleaner, smaller and slightly more efficient code ]

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