mm/percpu: remove unused PERCPU_DYNAMIC_EARLY_SLOTS

Since commit 40064aec ("percpu: replace area map allocator with
bitmap"), there's no place to use PERCPU_DYNAMIC_EARLY_SLOTS. So
clean it up.
Signed-off-by: Baoquan He <bhe@redhat.com>
Signed-off-by: Dennis Zhou <dennis@kernel.org>

include/linux/percpu.h

@@ -37,11 +37,10 @@
 /*
  * Percpu allocator can serve percpu allocations before slab is
  * initialized which allows slab to depend on the percpu allocator.
- * The following two parameters decide how much resource to
- * preallocate for this.  Keep PERCPU_DYNAMIC_RESERVE equal to or
- * larger than PERCPU_DYNAMIC_EARLY_SIZE.
+ * The following parameter decide how much resource to preallocate
+ * for this.  Keep PERCPU_DYNAMIC_RESERVE equal to or larger than
+ * PERCPU_DYNAMIC_EARLY_SIZE.
  */
-#define PERCPU_DYNAMIC_EARLY_SLOTS	128
 #define PERCPU_DYNAMIC_EARLY_SIZE	(12 << 10)
 
 /*