pwm: Drop useless member .of_pwm_n_cells of struct pwm_chip

pwm: Drop useless member .of_pwm_n_cells of struct pwm_chip

[ Upstream commit 4e77431cda4973f03d063c47f6ea313dfceebf16 ]

Apart from the two of_xlate implementations this member is write-only.
In the of_xlate functions of_pwm_xlate_with_flags() and
of_pwm_single_xlate() it's more sensible to check for args->args_count
because this is what is actually used in the device tree.

Acked-by: Douglas Anderson <dianders@chromium.org>
Link: https://lore.kernel.org/r/53d8c545aa8f79a920358be9e72e382b3981bdc4.1704835845.git.u.kleine-koenig@pengutronix.de
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Stable-dep-of: 3e551115aee0 ("pwm: meson: Add check for error from clk_round_rate()")
Signed-off-by: Sasha Levin <sashal@kernel.org>