hw/s390x/ccw: Replace dirname() with g_path_get_dirname()

As commit 3e015d8 ("use g_path_get_basename instead of basename")
said, g_path_get_dirname() should be preferred over dirname() since
the former is a portable utility function that has the advantage of not
modifying the string argument.

Replace dirname() with g_path_get_dirname().

Suggested-by: Cédric Le Goater <clg@redhat.com>
Signed-off-by: Zhao Liu <zhao1.liu@intel.com>
Message-ID: <20231221171921.57784-3-zhao1.liu@linux.intel.com>
Reviewed-by: Cédric Le Goater <clg@redhat.com>
Reviewed-by: Eric Farman <farman@linux.ibm.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>

hw/s390x/s390-ccw.c

@@ -77,6 +77,7 @@ static void s390_ccw_get_dev_info(S390CCWDevice *cdev,
 {
     unsigned int cssid, ssid, devid;
     char dev_path[PATH_MAX] = {0};
+    g_autofree char *tmp_dir = NULL;
     g_autofree char *tmp = NULL;
 
     if (!sysfsdev) {
@@ -93,7 +94,8 @@ static void s390_ccw_get_dev_info(S390CCWDevice *cdev,
 
     cdev->mdevid = g_path_get_basename(dev_path);
 
-    tmp = g_path_get_basename(dirname(dev_path));
+    tmp_dir = g_path_get_dirname(dev_path);
+    tmp = g_path_get_basename(tmp_dir);
     if (sscanf(tmp, "%2x.%1x.%4x", &cssid, &ssid, &devid) != 3) {
         error_setg_errno(errp, errno, "Failed to read %s", tmp);
         return;