drm/i2c/ch7006: Convert to dev_pm_ops

The I2C specific suspend and resume functions have been deprecated and
printing a warning on boot for over a year, dev_pm_ops should be used
instead so convert to that.

Also remove the suspend function since all it does is log.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Acked-by: Francisco Jerez <currojerez@riseup.net>
Signed-off-by: Dave Airlie <airlied@redhat.com>