grub: sample menu.lst file improvements

Two improvements to the menu.lst file:

 * Do not enforce any video mode, let the kernel use whatever it wants
   as the default, or let the user customize it when needed.

 * Use /dev/sda1 instead of /dev/hda1. Nowadays, most hard disk
   controllers are handled using libata, and therefore the disks are
   visible as /dev/sd<X>.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>