ARM: dts: msm: Correct the platform subtype for SM8150+SDXPRAIRIE

The platform subtype for SM8150+SDXPRAIRIE was mistakenly noted as 3
instead of 2. Hence, set it to the appropriate value.

Change-Id: I3e21679b115979b4d927f8a8af8cb620b9b773af
Signed-off-by: Raghavendra Rao Ananta <rananta@codeaurora.org>