arm64: dts: ti: k3-am62p: Enable Mailbox nodes at the board level

arm64: dts: ti: k3-am62p: Enable Mailbox nodes at the board level

Mailbox nodes defined in the top-level J722s/AM62p SoC dtsi files are
incomplete and may not be functional unless they are extended with a
chosen interrupt and connection to a remote processor.

Disable the Mailbox nodes in the dtsi files and only enable the ones
that are actually used on a given board.

Signed-off-by: Andrew Davis <afd@ti.com>
Link: https://lore.kernel.org/r/20241203174114.94751-1-afd@ti.com
Signed-off-by: Nishanth Menon <nm@ti.com>