ARM: omap: fix section mismatch errors in TWL PMIC driver

WARNING: drivers/mfd/built-in.o(.devinit.text+0x258): Section mismatch in reference from the function twl_probe() to the function .init.text:twl4030_power_init()
The function __devinit twl_probe() references
a function __init twl4030_power_init().
If twl4030_power_init is only used by twl_probe then
annotate twl4030_power_init with a matching annotation.

twl4030_power_init() references other __init marked functions, so
these too must become __devinit.

Acked-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>