pinctrl: renesas: r8a779a0: Remove incorrect AVB[01] pinmux configuration

AVB[01]_{MAGIC,MDC,MDIO,TXCREFCLK} are registered as both
PINMUX_SINGLE(fn) and PINMUX_IPSR_GPSR(fn) in the pinmux_data array.

The latter are correct, hence remove the former.
Without this fix, the Ethernet PHY is not operational on the MDIO bus.

Ported from Linux kernel commit a145c9a8674ac8fbfa1595276e1b6cbfc5139038 .

Signed-off-by: Hai Pham <hai.pham.ud@renesas.com>
Signed-off-by: LUU HOAI <hoai.luu.ub@renesas.com>
Fixes: 741a7370fc3b8b54 ("pinctrl: renesas: Initial R8A779A0 (V3U) PFC support")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/6fd217b71e83ba9a8157513ed671a1fa218b23b6.1674824958.git.geert+renesas@glider.be
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Cc: Geert Uytterhoeven <geert+renesas@glider.be>
Cc: Hai Pham <hai.pham.ud@renesas.com>
Cc: LUU HOAI <hoai.luu.ub@renesas.com>
Cc: Marek Vasut <marek.vasut+renesas@mailbox.org>