dt: Update all mainline bcm283x dt files for i2c0 pinctrl mux

BSC0 (aka i2c0) can me muxed via pinctrl to GPIOs 0&1, 28&29, or
44&45. These have different uses based on the platform (40pin header,
and CSI/DSI connectors), so add a pinctrl I2C mux between the
different options.

Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com>