soc: qcom: Insert poison value into DCC SRAM

Poison the DCC SRAM with a known poison value. This
value will help in finding which particular register
accesses are resulting in a bus hang on dump collection.

Change-Id: Ia7d367d015bf8193325087492d1ee7ff8db19d23
Signed-off-by: Satyajit Desai <sadesai@codeaurora.org>