ARM: dts: msm: Add the LCDB device node for PM2FALCON

LCDB supports the LCD display +ve/-ve bias. Add the device
node for it.

While at it, disable the LCDB module for PM3FALCON and remove
the dummy bias regulator nodes from falcon interposer.

CRs-Fixed: 1074468
Change-Id: I0aa4736aa0f2d6c6fe3b2e0d19c41df80c0975fe
Signed-off-by: Anirudh Ghayal <aghayal@codeaurora.org>