arm64: dts: sdm845: Fix up CPU topology

SDM845 implements ARM's Dynamiq architecture that allows the big and
LITTLE cores to exist in a single cluster sharing the L3 cache.

Fix the cpu-map to put all cpus into a single cluster.

Reviewed-by: Sudeep Holla <sudeep.holla@arm.com>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Signed-off-by: Amit Kucheria <amit.kucheria@linaro.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Andy Gross <agross@kernel.org>