ARM: dts: msm: Fix incorrect device-tree pickup for SM8150+SDX50

Due to the addition of a recent change (9fcd7689), the target platform
always picks up the sm8150+sdx50 2.5k display device tree, even
for a 4k display panel. Hence, with this fix, the platform picks
up the correct corresponding device tree for the platform.

Change-Id: If2538b48e8046d61727e7a138a896bc245993133
Signed-off-by: Raghavendra Rao Ananta <rananta@codeaurora.org>