arm64: dts: qcom: msm8992-bullhead: Fix cont_splash_mem size

Original google firmware reports 12 MiB:
[    0.000000] cma: Found cont_splash_mem@0, memory base 0x0000000003400000, size 12 MiB, limit 0xffffffffffffffff

which is actually 12*1024*1024 = 0xc00000.

This matches the aosp source [1]:
&cont_splash_mem {
	reg = <0 0x03400000 0 0xc00000>;
};

Fixes: 3cb6a271 ("arm64: dts: qcom: msm8992-bullhead: Fix cont_splash_mem mapping")
Fixes: 976d321f ("arm64: dts: qcom: msm8992: Make the DT an overlay on top of 8994")

[1] https://android.googlesource.com/kernel/msm.git/+/android-7.0.0_r0.17/arch/arm64/boot/dts/lge/msm8992-bullhead.dtsi#141



Signed-off-by: Petr Vorel <petr.vorel@gmail.com>
Reviewed-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20221226185440.440968-2-pevik@seznam.cz