ARM: dts: msm: remove old 8996 device trees

8996 v2.0 was an internal-only sample part which is no longer used.
Drop the associated device trees to save a little space.

Similarly, v2 and v3 RUMI and Sim platforms are not longer used.
Device trees for these can also be deleted.

Change-Id: I4ebbccf3d084936c934b50eb21372b307b340781
Signed-off-by: Matt Wagantall <mattw@codeaurora.org>