soc: qcom: memory_dump_v2: update cpu ctxt dump buffer size

Increase dump buffer size to accomodate all cpu registers and
other information dumped as a part of cpu context memory dump.

Change-Id: I9f9ebceaa45a4060cfcf099112121c31ef758b78
Signed-off-by: Aparna Das <adas@codeaurora.org>