mfd: wm5110: Fix defaults array based on testing

My automated test is back and now can check defaults against the actual
hardware. This patch updates the defaults array for the differences
detected and removes a couple of completely unused registers.
Signed-off-by: Charles Keepax <ckeepax@opensource.wolfsonmicro.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>