arm64: dts: renesas: r8a779f0: Add labels for rswitch ports

arm64: dts: renesas: r8a779f0: Add labels for rswitch ports

Introduce labels for each rswitch port in the form 'rswitch_portN'.
Those can be used to access rswitch port nodes directly, which is going
to be useful in reducing DT indentation slightly as well as in the DT
/aliases node to reference the rswitch ports as ethernetN interfaces.
No functional change.

Signed-off-by: Marek Vasut <marek.vasut+renesas@mailbox.org>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/20250118111344.361617-1-marek.vasut+renesas@mailbox.org
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>