ARM: dts: msm: add rtb trace support for msmthorium

Add RTB support to device tree node which enables RTB logging on
msmthorium. RTB logging provides useful debug information by logging
events to uncached buffer which can be processed from ramdumps in case
of device reset

Change-Id: Icaa880c5f24e6cd934a5dfff32122e930674dce7
Signed-off-by: Xiaogang Cui <xiaogang@codeaurora.org>