Set the grub timeout style to display the menu. By default it set to
'hidden' but can be changed to 'menu' to display the menu and then
wait for the timeout expire before booting the default entry.
Change-Id: I8c58407ef645d528dd77efe866bfe0389cbbbd33
Signed-off-by: Maksim Malchuk <maksim.malchuk@gmail.com>