pwm: sun4i: Consistently name driver data sun4ichip

The driver uses three different names for variables of type
sun4i_pwm_chip:

	$ git grep 'struct sun4i_pwm_chip \*' v6.8-rc1 -- drivers/pwm/pwm-sun4i.c
	v6.8-rc1:drivers/pwm/pwm-sun4i.c:static inline struct sun4i_pwm_chip *to_sun4i_pwm_chip(struct pwm_chip *chip)
	v6.8-rc1:drivers/pwm/pwm-sun4i.c:static inline u32 sun4i_pwm_readl(struct sun4i_pwm_chip *chip,
	v6.8-rc1:drivers/pwm/pwm-sun4i.c:static inline void sun4i_pwm_writel(struct sun4i_pwm_chip *chip,
	v6.8-rc1:drivers/pwm/pwm-sun4i.c:       struct sun4i_pwm_chip *sun4i_pwm = to_sun4i_pwm_chip(chip);
	v6.8-rc1:drivers/pwm/pwm-sun4i.c:static int sun4i_pwm_calculate(struct sun4i_pwm_chip *sun4i_pwm,
	v6.8-rc1:drivers/pwm/pwm-sun4i.c:       struct sun4i_pwm_chip *sun4i_pwm = to_sun4i_pwm_chip(chip);
	v6.8-rc1:drivers/pwm/pwm-sun4i.c:       struct sun4i_pwm_chip *sun4ichip;
	v6.8-rc1:drivers/pwm/pwm-sun4i.c:       struct sun4i_pwm_chip *sun4ichip = platform_get_drvdata(pdev);

"chip" is usually reserved for variables of type struct pwm_chip. So
pick sun4ichip as common name which better matches the type name than
sun4i_pwm.

Acked-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Link: https://lore.kernel.org/r/705f54a13b59fff50eaa345d8b1e0c691345b996.1707900770.git.u.kleine-koenig@pengutronix.de


Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>