Staging: speakup: fix an out-of-bounds error.

The cur_item variable from keyhelp.c is an index into a table of
messages.  The following condition should always hold:
MSG_FUNCNAMES_START + cur_item <= MSG_FUNCNAMES_END.
The check in keyhelp.c was wrong.  It allowed cur_item to be
incremented to an out-of-bounds value.

Signed-off-by: Christopher Brannon <chris@the-brannons.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>