arm64: dts: renesas: r8a77990-ebisu: use simple-audio-card

Current Ebisu board is using simple-scu-audio-card
which is used for Sampling Rate Convert, or MIXer, etc.
But, Ebisu is not using such feature.
Then, simple-audio-card is very enough.
This patch fixup it.

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>