arm: exynos5: Add NTC Thermistor attached to S3C-ADC

arm: exynos5: Add NTC Thermistor attached to S3C-ADC

This patch allows platform configurations to share information about
the NTC thermistor device attached to ADC port of S3C.

A platform configuration is required to initialize the ADC port for NTC
thermistor by calling "s3c_adc_ntc_init(pdev);" before registering the
NTC thermistor device. Then, registering a platform device,
s3c_device_adc_ntc_thermistor enables NTC thermistor for the platform.
(Modifications implemented by Grant Grundler)

BUG=chrome-os-partner:11688
TEST=Temperature is read using the sysfs entries in NTC Thermistor
driver: cat /sys/class/hwmon/hwmonX/device/temp1_input
X is 0, 1, 2 and 3

Change-Id: Ib7242f18adecf8602660decda670283c7ab68a0e
Signed-off-by: Naveen krishna Chatradhi <ch.naveen@samsung.com>
Signed-off-by: Abhilash Kesavan <a.kesavan@samsung.com>
Signed-off-by: Grant Grundler <grundler@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/28693
Tested-by: naveen krishna chatradhi <naveen@chromium.org>
Reviewed-by: Doug Anderson <dianders@chromium.org>
Commit-Ready: Doug Anderson <dianders@chromium.org>
Tested-by: Doug Anderson <dianders@chromium.org>