arm64: dts: msm8916: Add missing #phy-cells

commit b0ab681285aa66064f2de5b74191c0cabba381ff upstream.

Add a missing #phy-cells to the dsi-phy, to silence dtc warning.

Cc: Archit Taneja <architt@codeaurora.org>
Fixes: 305410ff ("arm64: dts: msm8916: Add display support")
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Reviewed-by: Archit Taneja <architt@codeaurora.org>
Signed-off-by: Andy Gross <andy.gross@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>