default or selected kernelversion does not have config value CONFIG_ARM_MHU_V3.
Result is shown for kernelversion 6.10-rc4

ARM MHUv3 Mailbox

modulename: arm_mhuv3.ko

configname: CONFIG_ARM_MHU_V3

Linux Kernel Configuration
└─>Device Drivers
└─>Mailbox Hardware Support
└─>Device Tree and Open Firmware support
└─>ARM MHUv3 Mailbox
Say Y here if you want to build the ARM MHUv3 controller driver,
which provides unidirectional mailboxes between processing elements.

ARM MHUv3 controllers can implement a varying number of extensions
that provides different means of transports: supported extensions
will be discovered and possibly managed at probe-time.

source code:
depends
CONFIG_MAILBOX
CONFIG_OF
CONFIG_COMPILE_TEST or CONFIG_HAS_IOMEM