This patch adds suspend/resume methods to the driver.

In suspend method irq line is disabled to avoid i2c
read/write errors from the interrupt handler as the
i2c bus itself could be in suspend state.
In resume function irq line will be re-enabled.
Signed-off-by: Ramakrishna Pallala <ramakrishna.pallala@intel.com>
Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org>