ARM: dts: NSP: MX65: add qca8k falling-edge, PLL properties

ARM: dts: NSP: MX65: add qca8k falling-edge, PLL properties

This patch enables two properties for the QCA8337 switches on the MX65.

Set the SGMII transmit clock to falling edge
"qca,sgmii-txclk-falling-edge" to conform to the OEM configuration [1].

The new explicit PLL enable option "qca,sgmii-enable-pll" is required
[2].

[1] https://git.kernel.org/netdev/net-next/c/b47f3feeca56
[2] https://git.kernel.org/netdev/net-next/c/4602cd1c1543

Signed-off-by: Matthew Hagan <mnhagan88@gmail.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>