genevn: optimize the process of ili7807s touch sending stylus cmd

tp:
According to fae's advice, add 20ms delay to fix the probabilistic failure of sending the stylus cmd after the firmware upgrade

Change-Id: I1eaf25d91556534c0d3f6fa8825e2e498a5facfa
Reviewed-on: https://gerrit.mot.com/2428503
SME-Granted: SME Approvals Granted
SLTApproved: Slta Waiver
Tested-by: Jira Key
Reviewed-by: Yeqing Wang <wangyq13@motorola.com>
Reviewed-by: Wei Deng <dengwei1@motorola.com>
Reviewed-by: Huosheng Liao <liaohs@motorola.com>
Submit-Approved: Jira Key

drivers/input/touchscreen/ili9882_mmi/ili9882_hostdl.c

@@ -428,6 +428,8 @@ static int ilitek_tddi_fw_iram_upgrade(u8 *pfw)
 	/* Waiting for fw ready sending first cmd */
 	if (!ilits->info_from_hex || (ilits->chip->core_ver < CORE_VER_1410))
 		mdelay(100);
+        else
+                mdelay(20);
 
 	return ret;
 }