[Turbo]Screen flash several times when set flash ON to take photo.

[Hannah Zhu]

Information:
phablet@ubuntu-phablet:~$ system-image-cli -i
current build number: 207
device name: turbo
channel: ubuntu-touch/rc-proposed/meizu-pd.en
last update: 2014-01-01 20:08:53
version version: 207
version ubuntu: 20161022
version device: 20160824-d33b825
version custom: 20160831-992-8-12

Precondition:
This issue only happened on Turbo device.

Step:
1. Open Camera app
2. Swipe up from the bottom, tap on the flash and set to "ON"
3. Press the screen to get focus and check the screen flash

Actual result:
Screen flash several times when get focus.

Expect result:
Get focus without screen flash. (Can compare with Krillin phenomenon.)