pinctrl: meson: meson8b: add the GPIOH pinmux settings for ETH_RXD{2,3}

pinctrl: meson: meson8b: add the GPIOH pinmux settings for ETH_RXD{2,3}

GPIOH_5 and GPIOH_6 can have two Ethernet related functions:
- GPIOH_5 can be ETH_TXD1 or ETH_RXD3
- GPIOH_6 can be ETH_TXD0 or ETH_RXD2

Add the bits for eth_rxd3_h and eth_rxd2_h so the ETH_RXD function can
be disabled when using the ETH_TXD function of GPIOH_{5,6}. No problem
was observed so far, but in theory this could lead to two different
signals being routed to the same pad (which could break Ethernet).

These settings were found in the public "Amlogic Ethernet controller
user guide":
http://openlinux.amlogic.com/@api/deki/files/75/=Amlogic_Ethenet_controller_user_Guide.pdf

Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Link: https://lore.kernel.org/r/20191226191425.3797490-1-martin.blumenstingl@googlemail.com
Reviewed-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>