pwm: bcm2835: Support for polarity setting via DT

This adds support for the third (optional) pwm cell to specify the
polarity, which is needed by display backlights for example.

Signed-off-by: Stefan Wahren <[e-mail]>
Reviewed-by: Eric Anholt <[e-mail]>
Signed-off-by: Thierry Reding <[e-mail]>

drivers/pwm/pwm-bcm2835.c

···
 	pc->chip.dev = &pdev->dev;
 	pc->chip.ops = &bcm2835_pwm_ops;
 	pc->chip.npwm = 2;
+	pc->chip.of_xlate = of_pwm_xlate_with_flags;
+	pc->chip.of_pwm_n_cells = 3;
 
 	platform_set_drvdata(pdev, pc);