ARM: msm: dts: Rename msm8994-pm to msm8994-v1-pm for MSM8994

With the availability of v1 and v2 hardware versions, a separate device
tree needs to be maintained for each of the hardware versions. Rename
msm8994-pm.dtsi to match the supported hardware revision.

Change-Id: I4fba7679898c46c0bd6062500eb500a45db83695
Signed-off-by: Karthik Parsha <kparsha@codeaurora.org>