ARM: dts: msm: Add dummy regulators in fsm9900

Add dummy regulators for LDO9, LDO20, LDO21, LVS1 in
all FSM9900 targets. SBL or TZ will configure and
control them. The dummy regulators satisfy various device
driver's DT requirements.

Change-Id: I5441f37f33ee5a743419d7cb499ac7a188b9c609
Acked-by: Kaushik Sikdar <ksikdar@qti.qualcomm.com>
Signed-off-by: Rohit Vaswani <rvaswani@codeaurora.org>