drivers/misc/apds990x.c: apds990x_chip_on() should depend on CONFIG_PM || CONFIG_PM_RUNTIME

Fixes this warning:

drivers/misc/apds990x.c: At top level:
drivers/misc/apds990x.c:613: warning: `apds990x_chip_on' defined but not used

Signed-off-by: Geert Uytterhoeven <[e-mail]>
Cc: Samu Onkalo <[e-mail]>
Cc: Jonathan Cameron <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

drivers/misc/apds990x.c

···
 	return ret;
 }
 
+#if defined(CONFIG_PM) || defined(CONFIG_PM_RUNTIME)
 static int apds990x_chip_on(struct apds990x_chip *chip)
 {
 	int err	 = regulator_bulk_enable(ARRAY_SIZE(chip->regs),
···
 	apds990x_mode_on(chip);
 	return 0;
 }
+#endif
 
 static int apds990x_chip_off(struct apds990x_chip *chip)
 {