ARM: dts: re-enable mhi boot logger channel for sm8150-sdxprairie

Boot logger channel was disabled temporarily for
sm8150-sdxprairie. Re-enabling the channel with memory
reduction on both host and device.

CRs-Fixed: 2488498
Change-Id: I9a4950a07cd1f03d46c965682f48d436090d9013
Acked-by: Bhaumik Vasav Bhatt <bbhatt@qti.qualcomm.com>
Signed-off-by: Sujeev Dias <sdias@codeaurora.org>