ARM: dts: sti: fixup sound frame-inversion for stihxxx-b2120.dtsi

[ Upstream commit f2466777 ]

frame-inversion is "flag" not "uint32".
This patch fixup it.

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Reviewed-by: Patrice Chotard <patrice.chotard@st.com>
Signed-off-by: Patrice Chotard <patrice.chotard@st.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>