mfd: AB3100 disable irq nosync

This will make the worker fire interrupt disable the AB3100 IRQ
without sync which resolves a race since the interrupt obviously
cannot wait for itself to complete while being handled.

Signed-off-by: Linus Walleij <linus.walleij@stericsson.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>