twl4030: simplified child creation code

twl4030: simplified child creation code

Minor cleanup to twl4030-core: define a helper function to populate
a single child node, and use it to replace six inconsistent versions
of the same logic.  Both object and source code shrink.

As part of this, some devices now have more IRQ resources:  battery
charger, keypad, ADC, and USB transceiver.  That will help to remove
some irq #defines that prevent this code from compiling on non-OMAP
platforms.

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