focaltech_0flash_mmi: ft fw file not found

Cebu focaltech touch invalid, tp fw name match fail
Recover fwname logic which is deleted by (CR):1687856
NO_PROP_NEEDED: 1687856 not merged to shm2018

Change-Id: I13500d1a4caa57882d10320332d2c0e6b164ece4
Signed-off-by: hujing3 <hujing3@lenovo.com>
Reviewed-on: https://gerrit.mot.com/1700585
SLTApproved: Slta Waiver
SME-Granted: SME Approvals Granted
Tested-by: Jira Key
Reviewed-by: Xiangpo Zhao <zhaoxp3@motorola.com>
Submit-Approved: Jira Key

drivers/input/touchscreen/focaltech_0flash_mmi/focaltech_ex_fun.c

@@ -1131,6 +1131,7 @@ static ssize_t doreflash_store(struct device *dev,
 
     memset(fwname, 0, sizeof(fwname));
     scnprintf(fwname, sizeof(fwname), "%s", buf);
+    fwname[count - 1] = '\0';
 
     mutex_lock(&input_dev->mutex);
     fts_fw_update_vendor_name(fwname);