input: synaptics_fw_update: Change permissions on lockdown sysfs entry

Permissions should be set to 0664 instead of 0777 for sysfs
entries.  Change them to pass CTS test.

Change-Id: I50237eaa917303efda0ad049649611bf1b6d9c31
Signed-off-by: Amy Maloche <amaloche@codeaurora.org>