input: touchscreen: synaptics_dsx: Remove fw_update sysfs entries

Remove the sysfs entrypoints to fw_update of synaptics_dsx
touch driver.

BUG: 32769717
Change-Id: I1b2ea28e6a8c5c6c583077fbc6801ebb17447a38
Git-commit: 2615c5f302441568e6dd20007bc5246d72837e80
Git-repo: https://android.googlesource.com/kernel/msm.git


Signed-off-by: Andrew Chant <achant@google.com>
Signed-off-by: Shantanu Jain <shjain@codeaurora.org>