firmware: arm_scmi: Fix uninitialized pointers with __free attr

firmware: arm_scmi: Fix uninitialized pointers with __free attr

Uninitialized pointers with `__free` attribute can cause undefined
behaviour as the memory assigned(randomly) to the pointer is freed
automatically when the pointer goes out of scope

arm doesn't have any bugs related to this as of now, but
it is better to initialize and assign pointers with `__free` attr
in one statement to ensure proper scope-based cleanup

Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Closes: https://lore.kernel.org/all/aPiG_F5EBQUjZqsl@stanley.mountain/
Signed-off-by: Ally Heev <allyheev@gmail.com>
Reviewed-by: Cristian Marussi <cristian.marussi@arm.com>
Message-Id: <20251105-aheev-uninitialized-free-attr-arm-v1-1-f7b6cb5d3361@gmail.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>