dmaengine: ti: Add NULL check in udma_probe()

In the Linux kernel, the following vulnerability has been resolved:

dmaengine: ti: Add NULL check in udma_probe()

devm_kasprintf() returns NULL when memory allocation fails. Currently,

udma_probe() does not check for this case, which results in a NULL

pointer dereference.

Add NULL check after devm_kasprintf() to prevent this issue.