ARM: dts: msm: Remove redundant sm8150p board overlay files

The sm8150p-[mtp|cdp|qrd]-overlay.dts files are redundant by the
fact that MSM and APQ SoCs can be overlayed onto the same board
(MTP, CDP or QRD). There's no need to explicitly add board files
specific to each SoC. It's the responsibilty of the bootloader
to pick the correct SoC and the board file required to be
overlayed on top of it. Hence, remove the redundant files from
the source.

Change-Id: I47d1269434b8ad0d064d0943f20410efb02172a3
Signed-off-by: Raghavendra Rao Ananta <rananta@codeaurora.org>