gpiolib: use the required minimum set of headers

Andy suggested we should keep a fine-grained scheme for includes and
only pull in stuff required within individual ifdef sections. Let's
revert commit dea69f2d1cc8 ("gpiolib: move all includes to the top of
gpio/consumer.h") and make the headers situation even more fine-grained
by only including the first level headers containing requireded symbols
except for bug.h where checkpatch.pl warns against including asm/bug.h.

Fixes: dea69f2d1cc8 ("gpiolib: move all includes to the top of gpio/consumer.h")
Suggested-by: Andy Shevchenko <[e-mail]>
Closes: https://lore.kernel.org/all/[e-mail]/
Reviewed-by: Andy Shevchenko <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Bartosz Golaszewski <[e-mail]>

include/linux/gpio/consumer.h

···
 #define __LINUX_GPIO_CONSUMER_H
 
 #include <linux/bits.h>
-#include <linux/bug.h>
 #include <linux/err.h>
-#include <linux/errno.h>
-#include <linux/kernel.h>
 #include <linux/types.h>
 
 struct acpi_device;
···
 					      const char *label);
 
 #else /* CONFIG_GPIOLIB */
+
+#include <linux/bug.h>
+#include <linux/kernel.h>
 
 static inline int gpiod_count(struct device *dev, const char *con_id)
 {
···
 int gpiod_enable_hw_timestamp_ns(struct gpio_desc *desc, unsigned long flags);
 int gpiod_disable_hw_timestamp_ns(struct gpio_desc *desc, unsigned long flags);
 #else
+
+#include <linux/bug.h>
+
 static inline int gpiod_enable_hw_timestamp_ns(struct gpio_desc *desc,
 					       unsigned long flags)
 {