soc: qcom: rpmpd: Check for null return of devm_kcalloc

Because of the possible failure of the allocation, data->domains might
be NULL pointer and will cause the dereference of the NULL pointer
later.
Therefore, it might be better to check it and directly return -ENOMEM
without releasing data manually if fails, because the comment of the
devm_kmalloc() says "Memory allocated with this function is
automatically freed on driver detach.".

Fixes: bbe3a66c ("soc: qcom: rpmpd: Add a Power domain driver to model corners")
Signed-off-by: Jiasheng Jiang <jiasheng@iscas.ac.cn>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20211231094419.1941054-1-jiasheng@iscas.ac.cn