ko splash.lyx: specify "mj" as CJK font

Now (thanks to d193cd05), the Korean splash.lyx compiles
out-of-the-box with pdflatex.

Thanks to Jürgen.

lib/examples/ko/splash.lyx

@@ -21,6 +21,7 @@
 \font_osf false
 \font_sf_scale 100 100
 \font_tt_scale 100 100
+\font_cjk mj
 \use_microtype false
 \use_dash_ligatures false
 \graphics default