arm64: dts: qcom: msm8994-angler: Disable cont_splash_mem

arm64: dts: qcom: msm8994-angler: Disable cont_splash_mem

As the default definition breaks booting angler:
[    1.862561] printk: console [ttyMSM0] enabled
[    1.872260] msm_serial: driver initialized
D -     15524 - pm_driver_init, Delta

cont_splash_mem was introduced in a670c22025c37, but the problem
manifested after commit '7e75faece7a6 ("fdt: Properly handle "no-map"
field in the memory region")'.

Disabling it because Angler's firmware does not report where the memory
is allocated (dmesg from downstream kernel):
[    0.000000] cma: Found cont_splash_mem@0, memory base 0x0000000000000000, size 16 MiB, limit 0x0000000000000000
[    0.000000] cma: CMA: reserved 16 MiB at 0x0000000000000000 for cont_splash_mem

Similar issue might be on Google Nexus 5X (lg-bullhead). Other MSM8992/4
are known to report correct address.

Fixes: a670c22025c37 ("arm64: dts: qcom: msm8994/8994-kitakami: Fix up the memory map")
Suggested-by: Konrad Dybcio <konradybcio@gmail.com>
Signed-off-by: Petr Vorel <petr.vorel@gmail.com>
Link: https://lore.kernel.org/r/20210622191019.23771-1-petr.vorel@gmail.com
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>