input: touchscreen: Add fw_name sysfs entry in Goodix driver

Add fw_name sysfs entry in Goodix driver. This entry allows
user to read and write firmware name from sysfs.

CRs-fixed: 555332

This patch is propagated from msm-3.18 kernel.
(commit: 3ebc6e4e4f092d622f2656aad320600ef11d0e07
input: touchscreen: Add fw_name sysfs entry in Goodix driver)

Change-Id: I69585d757f1a6dc40834a99ee67c872bf6f3ea13
Signed-off-by: Shantanu Jain <shjain@codeaurora.org>