input: synaptics_fw_update: Add sysfs entry for fw_name

Allow user to read and write firmware name from sysfs.
Also modify firmware update so it does not interfere with
suspend.

This patch is propagated from the msm-3.4 kernel.
(commit: b494b9aa7601e222a3e68fd12ab1c8cff1fcc519
input: synaptics_fw_update: Add sysfs entry for fw_name)

Change-Id: Iec1e3ef375211a8665443dcfd7b4e24a025fde93
Signed-off-by: Amy Maloche <amaloche@codeaurora.org>
Signed-off-by: Sudhakar Manapati <smanap@codeaurora.org>