PM: Fix oops in suspend/hibernate code related to failing ioremap()

When ioremap() fails (which might happen for some reason), we nicely
oops in suspend_nvs_save() due to NULL dereference by memcpy() in there.
Fail gracefully instead.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Len Brown <len.brown@intel.com>

kernel/power/nvs.c

@@ -105,7 +105,7 @@ int suspend_nvs_alloc(void)
 /**
  *	suspend_nvs_save - save NVS memory regions
  */
-void suspend_nvs_save(void)
+int suspend_nvs_save(void)
 {
 	struct nvs_page *entry;
 
@@ -114,8 +114,14 @@ void suspend_nvs_save(void)
 	list_for_each_entry(entry, &nvs_list, node)
 		if (entry->data) {
 			entry->kaddr = ioremap(entry->phys_start, entry->size);
+			if (!entry->kaddr) {
+				suspend_nvs_free();
+				return -ENOMEM;
+			}
 			memcpy(entry->data, entry->kaddr, entry->size);
 		}
+
+	return 0;
 }
 
 /**