ARM: dts: msm: Lower the minimum frequency for NPU devbw on SDM855

Add a zero frequency entry into the NPU devbw frequency table so that
the NPU devbw can actually vote for 0 when the device is suspended.

Change-Id: I70d3a7b9a356a3b9799307b6b0eb651c8306d050
Signed-off-by: Kyle Yan <kyan@codeaurora.org>