ARM: dts: msm: Update compatible string of LMH node for MSM8996

Update the compatible string of LMH node to differentiate
the LMH hardware in MSM8996 from its previous version.

Change-Id: I733334ae6f77a1f0167c8ef76a26967703e75aad
Signed-off-by: Ram Chandrasekar <rkumbako@codeaurora.org>