mfd: Convert Wolfson MFD drivers to use irq_data accessor function

Actually makes the code larger rathe rthan smaller but does provide some
isolation against core API changes.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

diff --cc drivers/mfd/wm831x-irq.c
Simple merge

diff --cc drivers/mfd/wm8350-irq.c
Simple merge

diff --cc drivers/mfd/wm8994-irq.c
Simple merge