arm64: dts: qcom: sdm845-db845c: Mark cont splash memory region as reserved

In the Linux kernel, the following vulnerability has been resolved: arm64: dts: qcom: sdm845-db845c: Mark cont splash memory region as reserved Adding a reserved memory region for the framebuffer memory (the splash memory region set up by the bootloader). It fixes a kernel panic (arm-smmu: Unhandled context fault at this particular memory region) reported on DB845c running v5.10.y.