ARM: dts: motorola-mapphone-common: remove unneeded "simple-graph-card"

ARM: dts: motorola-mapphone-common: remove unneeded "simple-graph-card"

Audio Graph Card is using "audio-graph-card" prefix instead of
"simple-graph-card", and moreover "widgets / routing" doesn't need it.
This patch removes unsupported "simple-graph-card" prefix from
motorola-mapphone-common.dtsi and vendor-prefixes.yaml.

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Reviewed-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Acked-by: Tony Lindgren <tony@atomide.com>
Link: https://lore.kernel.org/r/87r1ub39hq.wl-kuninori.morimoto.gx@renesas.com
Signed-off-by: Mark Brown <broonie@kernel.org>