percpu: update incorrect comment for this_cpu_*() operations

this_cpu_*() ops have been protected against both preemption and
interrupts for quite a while now.  We apparently forgot to update the
comment.  Fix it.
Signed-off-by: NTejun Heo <tj@kernel.org>
Cc: Christoph Lameter <cl@linux-foundation.org>

include/linux/percpu-defs.h

@@ -488,10 +488,8 @@ do {									\
 #define __this_cpu_dec_return(pcp)	__this_cpu_add_return(pcp, -1)
 
 /*
- * Operations with implied preemption protection.  These operations can be
- * used without worrying about preemption.  Note that interrupts may still
- * occur while an operation is in progress and if the interrupt modifies
- * the variable too then RMW actions may not be reliable.
+ * Operations with implied preemption/interrupt protection.  These
+ * operations can be used without worrying about preemption or interrupt.
  */
 #define this_cpu_read(pcp)		__pcpu_size_call_return(this_cpu_read_, pcp)
 #define this_cpu_write(pcp, val)	__pcpu_size_call(this_cpu_write_, pcp, val)