[PATCH 6/7] aw_pwm: implement pwmbus_channel_set_flags/get_flags

[vice-shore-grid_duck.com]

Summary

Split off https://reviews.freebsd.org/D60786 as requested by the maintainer.

PWM_POLARITY_INVERTED selects the active-low output level
(AW_PWM_CTRL_ACTIVE_LEVEL_HIGH cleared); the controller ignored polarity
altogether. Device trees pass it in the third pwms cell
(pwm_get_by_ofw_propidx() stores it in channel->flags), e.g. the PineTab
backlight: pwms = <&pwm 0 50000 PWM_POLARITY_INVERTED>.

[mmel]

sys/modules/allwinner/aw_pwm/Makefile

11

Why?