[PATCH] Fix oprofile on hyperthreaded P4's

[PATCH] Fix oprofile on hyperthreaded P4's

From: Philippe Elie <phil.el@wanadoo.fr>

- oprofile is currently only profiling one sibling.  Fix that with
  appropriate register settings.

- fix an oops which could occur if the userspace driver were to request a
  non-existent resource.

- in NMI handler counter_config[i].event is accessible from user space so
  user can change the event during profiling by echo xxx >
  /dev/oprofile/event

- event mask was wrong, the bit field is 6 bits length not 5, events
  SSE_INPUT_ASSIST and X87_SIMD_MOVES_UOP was affected by masking high bit of
  event number.