arm64: dts: ti: iot2050: Configure r5f cluster on basic variant in split mode

Lockstep mode is not supported here. So turn it off to avoid warnings
during startup.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Nishanth Menon <nm@ti.com>
Link: https://lore.kernel.org/r/3a241e50-80a3-992a-2445-345c629d7895@siemens.com