ALSA: compress_offload: fix remaining descriptor races in sound/core/compress_offload.c

ALSA: compress_offload: fix remaining descriptor races in sound/core/compress_offload.c

3d3f43fab4cf ("ALSA: compress_offload: improve file descriptors
installation for dma-buf") fixed some of descriptor races in
snd_compr_task_new(), but there's a couple more left.

We need to grab the references to dmabuf before moving them into
descriptor table - trying to do that by descriptor afterwards might
end up getting a different object, with a dangling reference left in
task->{input,output}

Fixes: 3d3f43fab4cf ("ALSA: compress_offload: improve file descriptors installation for dma-buf")
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Link: https://patch.msgid.link/20241229185232.GA1977892@ZenIV
Signed-off-by: Takashi Iwai <tiwai@suse.de>