perfcounters: remove ->nr_inherited

Impact: remove dead code

nr_inherited was not maintained correctly (not decremented) - and also
not used - remove it.
Signed-off-by: Ingo Molnar <mingo@elte.hu>

include/linux/perf_counter.h

@@ -164,7 +164,6 @@ struct perf_counter {
 	struct task_struct		*task;
 	struct file			*filp;
 
-	unsigned int			nr_inherited;
 	struct perf_counter		*parent;
 	/*
 	 * Protect attach/detach:

kernel/perf_counter.c

@@ -1308,7 +1308,6 @@ inherit_counter(struct perf_counter *parent_counter,
 	child_ctx->nr_counters++;
 
 	child_counter->parent = parent_counter;
-	parent_counter->nr_inherited++;
 	/*
 	 * inherit into child's child as well:
 	 */