drivers: perf: marvell_cn10k: fix an IS_ERR() vs NULL check

The devm_ioremap() function does not return error pointers.  It returns
NULL.

Fixes: 036a7584 ("drivers: perf: Add LLC-TAD perf counter support")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Link: https://lore.kernel.org/r/20211217145907.GA16611@kiliSigned-off-by: Will Deacon <will@kernel.org>

drivers/perf/marvell_cn10k_tad_pmu.c

@@ -312,7 +312,7 @@ static int tad_pmu_probe(struct platform_device *pdev)
 		regions[i].base = devm_ioremap(&pdev->dev,
 					       res->start,
 					       tad_pmu_page_size);
-		if (IS_ERR(regions[i].base)) {
+		if (!regions[i].base) {
 			dev_err(&pdev->dev, "TAD%d ioremap fail\n", i);
 			return -ENOMEM;
 		}