xen/common: move version printout under '?' keyhandler

Move Xen version printout from 'h' keyhandler to the new dedicated
handler '?'.

Suggested-by: Roger Pau Monné <roger@xenproject.org>
Signed-off-by: Denis Mukhin <dmukhin@ford.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>

xen/common/keyhandler.c

@@ -131,8 +131,6 @@ static void cf_check show_handlers(unsigned char key)
 
     printk("'%c' pressed -> showing installed handlers\n", key);
 
-    print_version();
-
     for ( i = 0; i < ARRAY_SIZE(key_table); i++ )
         if ( key_table[i].fn )
             printk(" key '%c' (ascii '%02x') => %s\n",
@@ -143,6 +141,8 @@ static void cf_check show_system_info(unsigned char key)
 {
     printk("'%c' pressed -> showing system information\n", key);
 
+    print_version();
+
     print_cmdline();
 }