ARM: dts: msm: Split 8994-v2.0 and 8994-v2.1 device trees

A minor revision of 8994 has been introduced, which is referred to
in software as v2.1. Create msm8994-v2.0.dtsi and msm8994-v2.1.dtsi
to distinguish between these versions, and create corresponding .dts
files for each of the supported board variants.

Both msm8994-v2.0.dtsi and msm8994-v2.1.dtsi include a base
msm8994-v2.dtsi file, where the bulk of the device configuration
exists. msm8994-v2.0.dtsi and msm8994-v2.1.dtsi are intended to
contain only version-specific data.

Change-Id: Ib16ed8c31fde218d17922376b33e3b5651f6a10a
Signed-off-by: Matt Wagantall <mattw@codeaurora.org>