Revert "Boost IO"

This reverts commit 54a1bee65191ef74c9da189120bc759003094e9f.
lcdc_ld9040: fix locking in lcd_sysfs_store_auto_brightness()

  * mutex was unlocked before the call to lcdc_ld9040_set_brightness()

Change-Id: I73765ca66f3dce908f93290d0e76da8e72c1d2ae