firmware: arm_scpi: Ensure scpi_info is not assigned if the probe fails

firmware: arm_scpi: Ensure scpi_info is not assigned if the probe fails

When scpi probe fails, at any point, we need to ensure that the scpi_info
is not set and will remain NULL until the probe succeeds. If it is not
taken care, then it could result use-after-free as the value is exported
via get_scpi_ops() and could refer to a memory allocated via devm_kzalloc()
but freed when the probe fails.

Link: https://lore.kernel.org/r/20220701160310.148344-1-sudeep.holla@arm.com
Cc: stable@vger.kernel.org # 4.19+
Reported-by: huhai <huhai@kylinos.cn>
Reviewed-by: Jackie Liu <liuyun01@kylinos.cn>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>