mako: Fix unbalanced disables for vibrator

[ 3101.348816] amp_enable: AMP_EN is set to 1
[ 3102.875995] ------------[ cut here ]------------
[ 3102.879749] WARNING: at android/kernel/drivers/regulator/core.c:1590 _reg
[ 3102.879779] unbalanced disables for 8921_l16
[ 3102.879779] Modules linked in:
[ 3102.879810] [<c0014380>] (unwind_backtrace+0x0/0x11c) from [<c007159c>] (
[ 3102.879810] [<c007159c>] (warn_slowpath_common+0x4c/0x64) from [<c0071634
[ 3102.879840] [<c0071634>] (warn_slowpath_fmt+0x2c/0x3c) from [<c02c5010>]
[ 3102.879871] [<c02c5010>] (_regulator_disable+0x30/0x23c) from [<c02c523c>
[ 3102.879871] [<c02c523c>] (regulator_disable+0x20/0x58) from [<c005bdcc>]
[ 3102.879901] [<c005bdcc>] (vibrator_power_set+0xfc/0x150) from [<c033fcb4>
[ 3102.879932] [<c033fcb4>] (android_vibrator_force_set+0x88/0x11c) from [<c

Change-Id: I54987c842384bd23b5daecddd6440d0ad0857523