power: twl4030: Move CONFIG_TWL4030_POWER to Kconfig

As requested, I added the CONFIG_TWL4030_POWER to Kconfig and made it
the implied default when selecting OMAP34XX as a platform.

Signed-off-by: Adam Ford <aford173@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/arm/mach-omap2/Kconfig b/arch/arm/mach-omap2/Kconfig
index 93fb320..6d8c3e4 100644
--- a/arch/arm/mach-omap2/Kconfig
+++ b/arch/arm/mach-omap2/Kconfig
@@ -79,6 +79,7 @@
 	imply SPL_POWER_SUPPORT
 	imply SPL_SERIAL_SUPPORT
 	imply SYS_THUMB_BUILD
+	imply TWL4030_POWER
 
 config OMAP44XX
 	bool "OMAP44XX SoC"