mfd: twl4030 IRQ handling update

- Move it into a separate file; clean and streamline it
 - Restructure the init code for reuse during secondary dispatch
 - Support both levels (primary, secondary) of IRQ dispatch
 - Use a workqueue for irq mask/unmask and trigger configuration

Code for two subchips currently share that secondary handler code.
One is the power subchip; its IRQs are now handled by this core,
courtesy of this patch.  The other is the GPIO module, which will
be supported through a later patch.

There are also minor changes to the header file, mostly related
to GPIO support; nothing yet in mainline cares about those.  A
few references to OMAP-specific symbols are disabled; when they
can all be removed, the TWL4030 support ceases being OMAP-specific.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Samuel Ortiz <sameo@openedhand.com>

drivers/mfd/Makefile

@@ -17,7 +17,7 @@ wm8350-objs			:= wm8350-core.o wm8350-regmap.o wm8350-gpio.o
 obj-$(CONFIG_MFD_WM8350)	+= wm8350.o
 obj-$(CONFIG_MFD_WM8350_I2C)	+= wm8350-i2c.o
 
-obj-$(CONFIG_TWL4030_CORE)	+= twl4030-core.o
+obj-$(CONFIG_TWL4030_CORE)	+= twl4030-core.o twl4030-irq.o
 
 obj-$(CONFIG_MFD_CORE)		+= mfd-core.o