Input: cyttsp - fix memcpy size param

memcpy param is wrong because of offset in bl_cmd, this may corrupt the
stack which may cause a crash.

Tested-by: Ferruh Yigit <fery@cypress.com> on TMA300-DVK
Signed-off-by: NFerruh Yigit <fery@cypress.com>
Acked-by: NJavier Martinez Canillas <javier@dowhile0.org>
Cc: stable@vger.kernel.org
Signed-off-by: NDmitry Torokhov <dmitry.torokhov@gmail.com>

drivers/input/touchscreen/cyttsp_core.c

@@ -133,7 +133,7 @@ static int cyttsp_exit_bl_mode(struct cyttsp *ts)
 	memcpy(bl_cmd, bl_command, sizeof(bl_command));
 	if (ts->pdata->bl_keys)
 		memcpy(&bl_cmd[sizeof(bl_command) - CY_NUM_BL_KEYS],
-			ts->pdata->bl_keys, sizeof(bl_command));
+			ts->pdata->bl_keys, CY_NUM_BL_KEYS);
 
 	error = ttsp_write_block_data(ts, CY_REG_BASE,
 				      sizeof(bl_cmd), bl_cmd);