hwtest: correct param image writing
hwtest: correct param image writing

This patch corrects params.bin writing of hwtest image.

Change-Id: I0a32a5dc5ef909ed8789b9c294bbea5604dc68df
Signed-off-by: Chanho Park <8ec285a53e21b773fd914e03c50e1b6431bc9aa8@samsung.com>

SamsungARTIK/build-artik