lib/percpu_ida.c: remove redundant includes

These three #includes seem to be completely redundant: Removing them
yields identical objdump -d output for each of {allyes,allno,def}config,
and neither included file end up in the generated dependency file through
some recursive include.  In total, about 50 lines are eliminated from
.percpu.o.cmd.

Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/lib/percpu_ida.c b/lib/percpu_ida.c
index 93d145e..f757151 100644
--- a/lib/percpu_ida.c
+++ b/lib/percpu_ida.c
@@ -19,13 +19,10 @@
 #include <linux/bug.h>
 #include <linux/err.h>
 #include <linux/export.h>
-#include <linux/hardirq.h>
-#include <linux/idr.h>
 #include <linux/init.h>
 #include <linux/kernel.h>
 #include <linux/percpu.h>
 #include <linux/sched.h>
-#include <linux/slab.h>
 #include <linux/string.h>
 #include <linux/spinlock.h>
 #include <linux/percpu_ida.h>