Add s3c-adc-battery driver

s3c-adc-battery is driver for monitoring and charging battery on
iPAQ H1930/H1940/RX1950.

It depends on s3c-adc driver to get battery voltage and current.

Signed-off-by: Vasily Khoruzhick <anarsoul@gmail.com>
Signed-off-by: Anton Vorontsov <cbouatmailru@gmail.com>