ARM: dts: msm: update mdp ramdump memory size for sm8150

This change updates reserve memory for display ramdump feature on
sm8150 target. This ramdump buffer address and size is configured by
bootloader and kernel will retain this memory forever to avoid overwrite.

Change-Id: I079d7e62ebcf1f77b4b3341d8f53589195e82b06
Signed-off-by: Narendra Muppalla <NarendraM@codeaurora.org>