pmdomain: ti: Add a null pointer check to the omap_prm_domain_init

devm_kasprintf() returns a pointer to dynamically allocated memory
which can be NULL upon failure. Ensure the allocation was successful
by checking the pointer validity.

Signed-off-by: Kunwu Chan <chentao@kylinos.cn>
Link: https://lore.kernel.org/r/20240118054257.200814-1-chentao@kylinos.cn


Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>