arm64: dts: ti: k3-j721e-main: Add #clock-cells property to serdes DT node

arm64: dts: ti: k3-j721e-main: Add #clock-cells property to serdes DT node

Add #clock-cells property to serdes DT node since the serdes is also now
modeled as a clock provider and include the input clocks "pll0_refclk"
and "pll1_refclk" which are parents to the clocks modeled by serdes.

Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
Reviewed-by: Aswath Govindraju <a-govindraju@ti.com>
Signed-off-by: Nishanth Menon <nm@ti.com>
Link: https://lore.kernel.org/r/20210603143427.28735-3-kishon@ti.com