eficonfig: add vertical scroll support

The current eficonfig menu does not support vertical scroll,
so it can not display the menu entries greater than
the console row size.

This commit add the vertial scroll support.
The console size is retrieved by
SIMPLE_TEXT_OUTPUT_PROTOCOL.QueryMode() service, then
calculates the row size for menu entry by subtracting
menu header and description row size from the console row size.
"start" and "end" are added in the efimenu structure.
"start" keeps the menu entry index at the top, "end" keeps
the bottom menu entry index. item_data_print() menu function
only draws the menu entry between "start" and "end".

This commit also fixes the issue that "Save" and "Quit"
entries can be moved by BKEY_PLUS in change boot order menu.

Signed-off-by: Masahisa Kojima <masahisa.kojima@linaro.org>
Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>

include/efi_config.h

@@ -49,6 +49,8 @@ struct eficonfig_entry {
  * @menu_header:	menu header string
  * @menu_desc:		menu description string
  * @list:		menu entry list structure
+ * @start:		top menu index to draw
+ * @end:		bottom menu index to draw
  */
 struct efimenu {
 	int delay;
@@ -57,6 +59,8 @@ struct efimenu {
 	char *menu_header;
 	const char *menu_desc;
 	struct list_head list;
+	int start;
+	int end;
 };
 
 /**