defconfig: sdxlemur: disable panic on oom on sdxlemur

sdx targets rely on oom killer to kill the processes as there is
no lmk. so, disable panic_on_oom on sdxlemur.

Change-Id: I4f06a0f4d6e45384d048bb5b9c61bee76d751896
Signed-off-by: Vijayanand Jitta <vjitta@codeaurora.org>