thermal: streamline get_trend callbacks

The .get_trend callback in struct thermal_zone_device_ops has
the prototype:
        int (*get_trend) (struct thermal_zone_device *, int,
                          enum thermal_trend *);
whereas the .get_trend callback in struct thermal_zone_of_device_ops
has:
        int (*get_trend)(void *, long *);

Streamline both prototypes and add the trip argument to the OF callback
aswell and use enum thermal_trend * instead of an integer pointer.

While the OF prototype may be the better one, this should be decided at
framework level and not on OF level.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Caesar Wang <wxt@rock-chips.com>
Cc: Zhang Rui <rui.zhang@intel.com>
Cc: Eduardo Valentin <edubezval@gmail.com>
Cc: linux-pm@vger.kernel.org
Reviewed-by: Keerthy <j-keerthy@ti.com>
Signed-off-by: Eduardo Valentin <edubezval@gmail.com>
Signed-off-by: Zhang Rui <rui.zhang@intel.com>