mfd: Set twl6030 irq_wake infrastructure up

TWL6030 devices have an interrupt line which is connected to
application processor like OMAP. These devices support multiple features
such as MMC card detect, USB cable detect, RTC interrupt, etc. that must
wake up the application processor.

With this change, TWL6030 client drivers can make use of
irq_wake() if the wakeup is desirable on it's irq events.

Signed-off-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>