[IA64] Move perfmon tables from thread_struct to pfm_context

This patch renders thread_struct->pmcs[] and thread_struct->pmds[]
OBSOLETE. The actual table is moved to pfm_context structure which
saves space in thread_struct (in turn saving space in task_struct
which frees up more space for kernel stacks).

Signed-off-by: Stephane Eranian <eranian@hpl.hp.com>
Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>