firmware: qcom: scm: smc: Handle missing SCM device

firmware: qcom: scm: smc: Handle missing SCM device

Commit ca61d6836e6f ("firmware: qcom: scm: fix a NULL-pointer
dereference") makes it explicit that qcom_scm_get_tzmem_pool() can
return NULL, therefore its users should handle this.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Link: https://lore.kernel.org/r/20241209-qcom-scm-missing-barriers-and-all-sort-of-srap-v2-5-9061013c8d92@linaro.org
Signed-off-by: Bjorn Andersson <andersson@kernel.org>