fpga: dfl: fme: fix return value check in in pr_mgmt_init()

In case of error, the function dfl_fme_create_region() returns ERR_PTR()
and never returns NULL. The NULL test in the return value check should
be replaced with IS_ERR().

Fixes: 29de762 ("fpga: dfl: fme: add partial reconfiguration sub feature support")
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Acked-by: Moritz Fischer <mdf@kernel.org>
Acked-by: Alan Tull <atull@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/fpga/dfl-fme-pr.c

@@ -420,7 +420,7 @@ static int pr_mgmt_init(struct platform_device *pdev,
 		/* Create region for each port */
 		fme_region = dfl_fme_create_region(pdata, mgr,
 						   fme_br->br, i);
-		if (!fme_region) {
+		if (IS_ERR(fme_region)) {
 			ret = PTR_ERR(fme_region);
 			goto destroy_region;
 		}