firmware: arm_scpi: Fix device_node reference leak in probe path

firmware: arm_scpi: Fix device_node reference leak in probe path

A device_node reference obtained from the device tree is not released
on all error paths in the arm_scpi probe path. Specifically, a node
returned by of_parse_phandle() could be leaked when the probe failed
after the node was acquired. The probe function returns early and
the shmem reference is not released.

Use __free(device_node) scope-based cleanup to automatically release
the reference when the variable goes out of scope.

Fixes: ed7ecb883901 ("firmware: arm_scpi: Add compatibility checks for shmem node")
Signed-off-by: Felix Gu <ustc.gu@gmail.com>
Message-Id: <20260121-arm_scpi_2-v2-1-702d7fa84acb@gmail.com>
Signed-off-by: Sudeep Holla <sudeep.holla@kernel.org>