dmaengine: ti: edma: Add some null pointer checks to the edma_probe

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/20240118031929.192192-1-chentao@kylinos.cn


Signed-off-by: Vinod Koul <vkoul@kernel.org>