arm: dts: spear13xx: Remove unused and undocumented "pl022,slave-tx-disable" property

Remove "pl022,slave-tx-disable" property which is both unused in the kernel
and undocumented. Most likely they are leftovers from downstream.

Signed-off-by: Rob Herring (Arm) <robh@kernel.org>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Link: https://lore.kernel.org/r/20241115193835.3623725-1-robh@kernel.org


Signed-off-by: Arnd Bergmann <arnd@arndb.de>