kconfig: fix warnings by specifing format arguments

Specify format arguments to fix warnings.

  HOSTCC  scripts/kconfig/gconf.o
/usr/src/lto/scripts/kconfig/gconf.c: In function 'on_introduction1_activate':
/usr/src/lto/scripts/kconfig/gconf.c:686:6: warning: format not a string literal and no format arguments
/usr/src/lto/scripts/kconfig/gconf.c: In function 'on_about1_activate':
/usr/src/lto/scripts/kconfig/gconf.c:704:6: warning: format not a string literal and no format arguments
/usr/src/lto/scripts/kconfig/gconf.c: In function 'on_license1_activate':
/usr/src/lto/scripts/kconfig/gconf.c:723:6: warning: format not a string literal and no format arguments

Signed-off-by: Peter Foley <pefoley2@verizon.net>
Signed-off-by: Michal Marek <mmarek@suse.cz>