firmware: xilinx: Fix dereferencing freed memory

Fix smatch warning:
drivers/firmware/xilinx/zynqmp.c:1288 zynqmp_firmware_remove()
error: dereferencing freed memory 'feature_data'

Use hash_for_each_safe for safe removal of hash entry.

Fixes: acfdd185 ("firmware: xilinx: Use hash-table for api feature check")
Reported-by: Nkernel test robot <lkp@intel.com>
Reported-by: NDan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: NTejas Patel <tejas.patel@xilinx.com>
Signed-off-by: NRajan Vaja <rajan.vaja@xilinx.com>
Link: https://lore.kernel.org/r/1612765883-22018-1-git-send-email-rajan.vaja@xilinx.comSigned-off-by: NMichal Simek <michal.simek@xilinx.com>

drivers/firmware/xilinx/zynqmp.c

@@ -2,7 +2,7 @@
 /*
  * Xilinx Zynq MPSoC Firmware layer
  *
- *  Copyright (C) 2014-2020 Xilinx, Inc.
+ *  Copyright (C) 2014-2021 Xilinx, Inc.
  *
  *  Michal Simek <michal.simek@xilinx.com>
  *  Davorin Mista <davorin.mista@aggios.com>
@@ -1280,12 +1280,13 @@ static int zynqmp_firmware_probe(struct platform_device *pdev)
 static int zynqmp_firmware_remove(struct platform_device *pdev)
 {
 	struct pm_api_feature_data *feature_data;
+	struct hlist_node *tmp;
 	int i;
 
 	mfd_remove_devices(&pdev->dev);
 	zynqmp_pm_api_debugfs_exit();
 
-	hash_for_each(pm_api_features_map, i, feature_data, hentry) {
+	hash_for_each_safe(pm_api_features_map, i, tmp, feature_data, hentry) {
 		hash_del(&feature_data->hentry);
 		kfree(feature_data);
 	}