arm64: dts: qcom: sdm845-db845c-navigation-mezzanine: Add cma heap for libcamera softisp support

libcamera softisp requires a linux,cma heap export in order to support
user-space debayering, 3a and export to other system components such as
pipewire, Firefox/Chromium - Hangouts, Zoom etc.

Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
Reviewed-by: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>
Link: https://lore.kernel.org/r/20241025-b4-linux-next-24-10-25-camss-dts-fixups-v1-6-cdff2f1a5792@linaro.org


Signed-off-by: Bjorn Andersson <andersson@kernel.org>