clk: renesas: r9a07g043: Add ethernet clock sources

Ethernet reference clock can be sourced from PLL5_500 or PLL6. Add
support for ethernet source clock selection using SEL_PLL_6_2 mux.

Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
Reviewed-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Link: https://lore.kernel.org/r/20220402074626.25624-3-biju.das.jz@bp.renesas.com


Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>