ASoC: wm5110: Add in OSR controls for OUT5/6

There are no OSR controls on outputs 1-4 on wm5110, however when these
were removed the ones on output 5 and 6 were also accidentally removed,
but those actually exist. This patch adds these controls back in.

Signed-off-by: Charles Keepax <ckeepax@opensource.wolfsonmicro.com>
Signed-off-by: Mark Brown <broonie@linaro.org>