libipt: remove unused functions

The following functions are not used.  Remove them.

  pt_get_decoder_raw
  pt_get_decoder_begin
  pt_get_decoder_end

Change-Id: I97803e7006ab169580ff363d3c0d3a66afb22cc4
Signed-off-by: Markus Metzger <markus.t.metzger@intel.com>
libipt: fix abbreviation

Intel(R) Processor Trace is correctly abbreviated Intel PT.  Fix it.

Change-Id: Ied231479d1bad74e6cd3839386613b0ebe894b41
Signed-off-by: Markus Metzger <markus.t.metzger@intel.com>