ARM: dts: am335x-sl50: Enable BQ32000 Real Time Clock.

Add support for the BQ32000 Real Time Clock connected to the I2C bus
and disable the AM335x Real Time Clock.

Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>