mfd: twl4030: cleanup symbols and OMAP dependency

Finish removing dependency of TWL driver stack on platform-specific
IRQ definitions ... and remove the build dependency on OMAP.

This lets the TWL4030 code be included in test builds for most
platforms, and will make it easier for non-OMAP folk to update
most of this code for new APIs etc.

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>