libnvdimm: release ida resources

ida instances allocate some internal memory for ->free_bitmap in
addition to the base 'struct ida'.  Use ida_destroy() to release that
memory at module_exit().

Reported-by: Johannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
diff --git a/drivers/nvdimm/core.c b/drivers/nvdimm/core.c
index 182a93f..847532d 100644
--- a/drivers/nvdimm/core.c
+++ b/drivers/nvdimm/core.c
@@ -648,6 +648,9 @@
 	nd_region_exit();
 	nvdimm_exit();
 	nvdimm_bus_exit();
+	nd_region_devs_exit();
+	nvdimm_devs_exit();
+	ida_destroy(&nd_ida);
 }
 
 MODULE_LICENSE("GPL v2");