platform/x86: dell_rbu: Fix list usage

Pass the correct list head to list_for_each_entry*() when looping through
the packet list.

Without this patch, reading the packet data via sysfs will show the data
incorrectly (because it starts at the wrong packet), and clearing the
packet list will result in a NULL pointer dereference.

Fixes: d19f359 ("platform/x86: dell_rbu: don't open code list_for_each_entry*()")
Signed-off-by: Stuart Hayes <stuart.w.hayes@gmail.com>
Link: https://lore.kernel.org/r/20250609184659.7210-3-stuart.w.hayes@gmail.com
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>

Author: stuartwhayes

drivers/platform/x86/dell/dell_rbu.c

@@ -292,7 +292,7 @@ static int packet_read_list(char *data, size_t * pread_length)
 	remaining_bytes = *pread_length;
 	bytes_read = rbu_data.packet_read_count;
 
-	list_for_each_entry(newpacket, (&packet_data_head.list)->next, list) {
+	list_for_each_entry(newpacket, &packet_data_head.list, list) {
 		bytes_copied = do_packet_read(pdest, newpacket,
 			remaining_bytes, bytes_read, &temp_count);
 		remaining_bytes -= bytes_copied;
@@ -315,7 +315,7 @@ static void packet_empty_list(void)
 {
 	struct packet_data *newpacket, *tmp;
 
-	list_for_each_entry_safe(newpacket, tmp, (&packet_data_head.list)->next, list) {
+	list_for_each_entry_safe(newpacket, tmp, &packet_data_head.list, list) {
 		list_del(&newpacket->list);
 
 		/*