speakup: Fix bogus caps on speaking unicode characters

commit 33590c18 ("speakup: Support spelling unicode characters")
mistakenly passed unicode characters to IS_CHAR(), which only
supports latin1.  Let's assume non-latin1 is lower case, like is done
in spell_word().

Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
Reviewed-by: Chris Brannon <chris@the-brannons.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>