doc: board: typo GIUD Microchip MPFS Icicle Kit doc

%s/GIUD/GUID/

Fixes: 9e550e18 ("doc: board: Add Microchip MPFS Icicle Kit doc")
Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
Reviewed-by: Bin Meng <bmeng@tinylab.org>