[PATCH] boot: boot menu up to 35 devices with letters and possible pages

[Ivan Ivanov]

Extend boot menu: make it possible to select the boot menu entries
with ID larger than 10 by pressing a corresponding letter key. If
there are more than 18 devices, then a boot menu splits into two
pages; you can switch between the pages by pressing the ENTER key.
NOTE: now to access the TPM you need to press the M key. It makes more
sense, because Trusted is adjective while Module is noun - and adds
more convenience, because M letter is at the end of keyboard's 3rd row
of letters, not in the middle of them

Signed-off-by: Ivan Ivanov <qmastery16 at gmail.com>