defconfig: Change panic timeout for target sa8155

Change panic timeout for target sa8155 so that the device
reboots immediately when a kernel panic is encountered,
instead of waiting for 5 seconds.

Change-Id: Id0a9c5e0c5cc4682b6b5a3d5a231a1aade6258b8
Signed-off-by: Bharathraj Nagaraju <snbraj@codeaurora.org>