CVE-2023-54319 pinctrl: at91-pio4: check return value of devm_kasprintf()

In the Linux kernel, the following vulnerability has been resolved: pinctrl: at91-pio4: check return value of devmkasprintf devmkasprintf returns a pointer to dynamically allocated memory. Pointer could be NULL in case allocation fails. Check pointer validity. Identified with coccinelle kmerr.coc...