input: synaptics_dsx: change permission for sysfs secure_touch_enable

Sysfs secure_touch_enable has permission 666. Remove write access
for "others" to avoid security concerns.

This patch is propagated from msm-3.10 kernel
(commit: 313901e04c32b552deb4914311844ac6cda08238
input: synaptics_dsx: change permission for sysfs secure_touch_enable)

CRs-fixed: 763326
Change-Id: Ifcc34d418fb14af21440d2dd7200d125b02f85dd
Signed-off-by: Mao Li <maol@codeaurora.org>
Signed-off-by: Sudhakar Manapati <smanap@codeaurora.org>