[IA64] Add API for allocating Dynamic TR resource.

Dynamic TR resource should be managed in the uniform way.
Add two interfaces for kernel:
ia64_itr_entry: Allocate a (pair of) TR for caller.
ia64_ptr_entry: Purge a (pair of ) TR by caller.

Signed-off-by: Xiantao Zhang <xiantao.zhang@intel.com>
Signed-off-by: Anthony Xu <anthony.xu@intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
diff --git a/arch/ia64/kernel/mca_asm.S b/arch/ia64/kernel/mca_asm.S
index 8bc7d25..a06d465 100644
--- a/arch/ia64/kernel/mca_asm.S
+++ b/arch/ia64/kernel/mca_asm.S
@@ -219,8 +219,13 @@
 	mov r20=IA64_TR_CURRENT_STACK
 	;;
 	itr.d dtr[r20]=r16
+	GET_THIS_PADDR(r2, ia64_mca_tr_reload)
+	mov r18 = 1
 	;;
 	srlz.d
+	;;
+	st8 [r2] =r18
+	;;
 
 done_tlb_purge_and_reload: