ARM: dts: msm: Increase FCM dump size by 8k on sdm845

Increase FCM dump buffer size to include GIC registers to capture
interrupt status, configuration & GIC error details to debug issues
related to GIC.

Change-Id: Iebfc3fb4a0d006a31c7cf5b7a3dad7deaa237be0
Signed-off-by: Channagoud Kadabi <ckadabi@codeaurora.org>