arm64: dts: allwinner: pinephone: Set audio card name

Add the "PinePhone" name to the sound card: this will make
upstreaming an ALSA UCM config easier as we can use a unique name.

It also avoids an issue where the default card name is truncated.

Signed-off-by: Arnaud Ferraris <arnaud.ferraris@collabora.com>
[Samuel: Split out change, updated commit message]
Signed-off-by: Samuel Holland <samuel@sholland.org>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Link: https://lore.kernel.org/r/20210430035859.3487-8-samuel@sholland.org