input: touchscreen: synaptics: Remove fw_update sysfs entries

Remove the sysfs entrypoints to fw_update of synaptics driver.

BUG: 32769717
Change-Id: I710cb37a8b5382dce7aa6a1d8748be5853a18a7a
Git-commit: 2615c5f302441568e6dd20007bc5246d72837e80
Git-repo: https://android.googlesource.com/kernel/msm.git


Signed-off-by: Andrew Chant <achant@google.com>
Signed-off-by: Vevek Venkatesan <vevekv@codeaurora.org>