Fix inconsistent keymap in it(intl) keyboard

Italian keyboard has 'ì' and 'ù' characters. The variant "Italian
(intl., with dead keys)" is erroneously associating these keys to
the 'í' and 'ú' symbols, respectively.

This patch associates the two keys in the keyboard variant with the
correct symbols (i.e., 'ì' and 'ù').

Signed-off-by: Alessandro Pellegrini <pellegrini@dis.uniroma1.it>