ARM: dts: porter: fix JP3 jumper description

When finishing the Porter sound support patch, I managed to call the JP3
jumper SW3 in the comment.  Fix this  along with (also miscalled) jumper
positions...

Fixes: 493b4da7 ("ARM: dts: porter: add sound support")
Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Acked-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>