pwm: Move contents of sysfs.c into core.c

With the upcoming restructuring having all in a single file simplifies
things a bit. The relevant and somewhat visible changes are:

 - Some dropped prototypes from include/linux/pwm.h that were only
   necessary that core.c has a declaration of the symbols defined in
   sysfs.c. The respective functions are static now.

 - The pwm class now also exists if CONFIG_SYSFS isn't enabled. Having
   CONFIG_SYSFS is not very relevant today, but even without it the
   class and device stuff still provides lifetime tracking.

 - Both files had an initcall, these are merged into a single one now.
   Instead of a big #ifdef block for CONFIG_DEBUG_FS, a single
   if (IS_ENABLED(CONFIG_DEBUG_FS)) is used now. This increases compile
   coverage a bit and is a tad nicer on the eyes.

Link: https://lore.kernel.org/r/9e2d39a5280d7dda5bfc6682a8aef510148635b2.1710670958.git.u.kleine-koenig@pengutronix.deSigned-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>

drivers/pwm/Kconfig

@@ -29,10 +29,6 @@ menuconfig PWM
 
 if PWM
 
-config PWM_SYSFS
-	bool
-	default y if SYSFS
-
 config PWM_DEBUG
 	bool "PWM lowlevel drivers additional checks and debug messages"
 	depends on DEBUG_KERNEL

drivers/pwm/Makefile

 # SPDX-License-Identifier: GPL-2.0
 obj-$(CONFIG_PWM)		+= core.o
-obj-$(CONFIG_PWM_SYSFS)		+= sysfs.o
 obj-$(CONFIG_PWM_AB8500)	+= pwm-ab8500.o
 obj-$(CONFIG_PWM_APPLE)		+= pwm-apple.o
 obj-$(CONFIG_PWM_ATMEL)		+= pwm-atmel.o

include/linux/pwm.h

@@ -630,17 +630,4 @@ static inline void pwm_remove_table(struct pwm_lookup *table, size_t num)
 }
 #endif
 
-#ifdef CONFIG_PWM_SYSFS
-void pwmchip_sysfs_export(struct pwm_chip *chip);
-void pwmchip_sysfs_unexport(struct pwm_chip *chip);
-#else
-static inline void pwmchip_sysfs_export(struct pwm_chip *chip)
-{
-}
-
-static inline void pwmchip_sysfs_unexport(struct pwm_chip *chip)
-{
-}
-#endif /* CONFIG_PWM_SYSFS */
-
 #endif /* __LINUX_PWM_H */