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.

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