ARM: dts: msm: Reduce the qdss bam blk size

Using qdss bam block size (2KB) larger than the data fifo size of 1.5KB
causes a hang resulting in no data being streamed out. Reduce qdss bam
block size to 512bytes to fix this.

Change-Id: I24a4e171a65d37d3fb899897138b0676a3d41dd2
Signed-off-by: Pan Fang <fangpan@codeaurora.org>
Signed-off-by: Xiaogang Cui <xiaogang@codeaurora.org>