sonypi: suspend/resume callbacks should be conditionally compiled on CONFIG_PM_SLEEP

This will fix warnings like following when CONFIG_PM_SLEEP is not set:

warning: 'xxx_suspend' defined but not used [-Wunused-function]
warning: 'xxx_resume' defined but not used [-Wunused-function]

Because
SET_SYSTEM_SLEEP_PM_OPS(suspend_fn, resume_fn)

Only references the callbacks on CONFIG_PM_SLEEP (instead of CONFIG_PM).

Cc: Mattia Dongili <[e-mail]>
Cc: Arnd Bergmann <[e-mail]>
Cc: [e-mail]
Signed-off-by: Yuanhan Liu <[e-mail]>
Signed-off-by: Fengguang Wu <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/char/sonypi.c

···
 	return 0;
 }
 
-#ifdef CONFIG_PM
+#ifdef CONFIG_PM_SLEEP
 static int old_camera_power;
 
 static int sonypi_suspend(struct device *dev)