arm64: dts: qcom: msm8916-samsung-a5u: Fix iris compatible

Unlike most MSM8916 boards, samsung-a5u uses WCN3660B instead of
WCN3620 to support the 5 GHz band additionally.

WCN3660B has similar requirements as WCN3620, but it needs the XO
clock to run at 48 MHz instead of 19.2 MHz. So far it was possible
to describe that configuration using the qcom,wcn3680 compatible.

However, as of commit 8490987b ("wcn36xx: Hook and identify RF_IRIS_WCN3680"),
the wcn36xx driver will now use the qcom,wcn3680 compatible
to enable functionality specific to WCN3680. In particular,
WCN3680 supports 802.11ac, which is not available in WCN3660B.

Use the new qcom,wcn3660b compatible to describe the chip properly.

Fixes: 0d705199

 ("arm64: dts: msm8916-samsung-a5u: Override iris compatible")
Signed-off-by: Stephan Gerhold <stephan@gerhold.net>
Link: https://lore.kernel.org/r/20210106102134.59801-4-stephan@gerhold.net
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>