thermal/drivers/qcom/lmh: Check for SCM availability at probe

Up until now, the necessary scm availability check has not been
performed, leading to possible null pointer dereferences (which did
happen for me on RB1).

Fix that.

Fixes: 53bca371 ("thermal/drivers/qcom: Add support for LMh driver")
Cc: <stable@vger.kernel.org>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Bjorn Andersson <andersson@kernel.org>
Signed-off-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/20240308-topic-rb1_lmh-v2-2-bac3914b0fe3@linaro.org