defconfig: arm64: sdm855: Enable dynamic device file minor for audio

Enable CONFIG_SND_DYNAMIC_MINORS to allocate the minor numbers of
ALSA device files in /dev/snd/ dynamically. This allows to have
more than 8 sound cards.

Change-Id: I63e8dc37a9e476961718dbe05afbde0e7863a043
Signed-off-by: Meng Wang <mwang@codeaurora.org>