arm64: Kconfig.platforms: remove useless select for ARCH_K3

After patch done on TI_MESSAGE_MANAGER[1] and TI_SCI_PROTOCOL[2] driver
select on ARCH_K3 are not needed anymore.
Select MAILBOX by default is not needed anymore[3],
PM_GENERIC_DOMAIN if PM was enabled by default so not needed.

Remove it and give possibility to enable this driver in modules.

[1] https://lore.kernel.org/all/20180828005311.8529-1-nm@ti.com/
[2] https://lore.kernel.org/all/20250220-ti-firmware-v2-1-ff26883c6ce9@baylibre.com/
[3] https://lore.kernel.org/all/20250507135213.g6li6ufp3cosxoys@stinging/



Signed-off-by: Guillaume La Roque <glaroque@baylibre.com>
Link: https://lore.kernel.org/r/20250519-kconfig-v2-1-56c1a0137a0f@baylibre.com


Signed-off-by: Vignesh Raghavendra <vigneshr@ti.com>