meson_pwm_calc() is the last function that accepts a struct
meson_pwm_channel. meson_pwm_enable(), meson_pwm_disable() and
meson_pwm_apply() for example are all taking a struct pwm_device as
parameter. When they need the struct meson_pwm_channel these functions
simply call pwm_get_chip_data() internally.

Make meson_pwm_calc() consistent with the other functions in the
meson-pwm driver by passing struct pwm_device to it as well. The value
of the "id" parameter is actually pwm->hwpwm, but the driver never read
the "id" parameter, which is why there's no replacement for it in the
new code.

No functional changes.
Reviewed-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>