Fix console reattach after detach

This avoids lockups seen on detach / reattach
when the host IPL is in process.

kestrel/src/kestrel.c

@@ -2407,13 +2407,9 @@ int attach_to_host_console(const struct shell *shell)
     // Deactivate interrupts on entering critical section
     int key = irq_lock();
 
-    // Reset VUART1 FIFO pointers
-    vuart1_incoming_interrupt_transient_buffer_pos = 0;
-    vuart1_incoming_interrupt_transient_buffer_overflow = 0;
-    vuart1_outgoing_buffer_read_pos = 0;
-    vuart1_outgoing_buffer_write_pos = 0;
-    vuart1_incoming_buffer_read_pos = 0;
-    vuart1_incoming_buffer_write_pos = 0;
+    // Reset VUART1 ring buffer pointers
+    vuart1_outgoing_buffer_read_pos = vuart1_outgoing_buffer_write_pos;
+    vuart1_incoming_buffer_write_pos = vuart1_incoming_buffer_read_pos;
 
     host_console_service_task_requested = 1;
     host_console_service_task_shell = shell;