arm64: dts: mt8195: Fix CPU map for single-cluster SoC

MT8195 features the ARM DynamIQ technology and combines both four
Cortex-A78 (big) and four Cortex-A55 (LITTLE) CPUs in one cluster:
fix the CPU map to reflect that.

Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Fixes: 37f25828 ("arm64: dts: Add mediatek SoC mt8195 and evaluation board")
Link: https://lore.kernel.org/r/20230126103526.417039-2-angelogioacchino.delregno@collabora.com


Signed-off-by: Matthias Brugger <matthias.bgg@gmail.com>