arm64: dts: renesas: salvator-common: Describe PCIe/USB3.0 clock generator

arm64: dts: renesas: salvator-common: Describe PCIe/USB3.0 clock generator

Describe the 9FGV0841 PCIe and USB3.0 clock generator present on both
Salvator-X and Salvator-XS boards.  The clock generator supplies 100 MHz
differential clock for both PCIe ports, as well as for the USB 3.0 PHY.

Signed-off-by: Marek Vasut <marek.vasut+renesas@mailbox.org>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://patch.msgid.link/20260118135038.8033-8-marek.vasut+renesas@mailbox.org
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>