defconfig: enable LCDB support in SDM660-perf_defconfig

LCDB driver exposes regulators to control the positive and
negative voltage bias for the LCD display panel. It also
allows ability to configure for the various bias-voltage
parameters.

Change-Id: I339345520a47c117e37e57a7b1f37ff2aead3dd8
Signed-off-by: Ashay Jaiswal <ashayj@codeaurora.org>