CVE-2024-50160: NULL Pointer Dereference

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

ALSA: hda/cs8409: Fix possible NULL dereference

If snd_hda_gen_add_kctl fails to allocate memory and returns NULL, then NULL pointer dereference will occur in the next line.

Since dolphin_fixups function is a hda_fixup function which is not supposed to return any errors, add simple check before dereference, ignore the fail.

Found by Linux Verification Center (linuxtesting.org) with SVACE.