build: set bootdelay 0 for hwtest
build: set bootdelay 0 for hwtest

This patch changes bootdelay of u-boot from 3 to 0 to reduce
booting time during hwtest.

Change-Id: I6dadc9d96eb2423a82cb4a5258ef8f7058a45ce6
Signed-off-by: Chanho Park <8ec285a53e21b773fd914e03c50e1b6431bc9aa8@samsung.com>

SamsungARTIK/build-artik