input: add support for FN1 - FN10 on crosswire kbd

Chromebooks and the sandbox use a crosswire keyboard with function keys
FN1 - FN10. These keys are needed when running UEFI applications like GRUB
or the UEFI SCT.

Add support for these keys when translating from key codes to
ECMA-48 (or withdrawn ANSI 3.64) escape sequences.

All escape sequences start with 0x1b. So we should not repeat this
byte in the kbd_to_ansi364 table.

For testing use:

sandbox_defconfig + CONFIG_EFI_SELFTEST=y

$ ./u-boot -D -l

=> setenv efi_selftest extended text input
=> bootefi selftest

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Reviewed-by: Simon Glass <sjg@chromium.org>