remoteproc: qcom_wcnss: Fix NULL vs IS_ERR() bug in wcnss_alloc_memory_region()

The devm_ioremap_resource_wc() function never returns NULL, it returns
error pointers. Update the checking to match.

Fixes: c70b9d5fdcd7 ("remoteproc: qcom: Use of_reserved_mem_region_* functions for "memory-region"")
Signed-off-by: Dan Carpenter <[e-mail]>
Link: https://lore.kernel.org/r/09a43[e-mail]
Signed-off-by: Bjorn Andersson <[e-mail]>

drivers/remoteproc/qcom_wcnss.c

···
 	wcnss->mem_phys = wcnss->mem_reloc = res.start;
 	wcnss->mem_size = resource_size(&res);
 	wcnss->mem_region = devm_ioremap_resource_wc(wcnss->dev, &res);
-	if (!wcnss->mem_region) {
+	if (IS_ERR(wcnss->mem_region)) {
 		dev_err(wcnss->dev, "unable to map memory region: %pR\n", &res);
-		return -EBUSY;
+		return PTR_ERR(wcnss->mem_region);
 	}
 
 	return 0;