smdk4412-common: camera: properly enable touch to focus mode

Touch to focus is not properly enforced unless the focus mode
is set to FOCUS_MODE_TOUCH.

https://github.com/CyanogenMod/android_kernel_samsung_smdk4412/blob/cm-11.0/drivers/media/video/s5c73m3.c#L1857

Change-Id: I67236ae7ae687fbc0b7450102d744472a81def99