dt-bindings: net: mediatek: remove wrongly added clocks and SerDes

dt-bindings: net: mediatek: remove wrongly added clocks and SerDes

Several clocks as well as both sgmiisys phandles were added by mistake
to the Ethernet bindings for MT7988. Also, the total number of clocks
didn't match with the actual number of items listed.

This happened because the vendor driver which served as a reference uses
a high number of syscon phandles to access various parts of the SoC
which wasn't acceptable upstream. Hence several parts which have never
previously been supported (such SerDes PHY and USXGMII PCS) are going to
be implemented by separate drivers. As a result the device tree will
look much more sane.

Quickly align the bindings with the upcoming reality of the drivers
actually adding support for the remaining Ethernet-related features of
the MT7988 SoC.

Fixes: c94a9aabec36 ("dt-bindings: net: mediatek,net: add mt7988-eth binding")
Signed-off-by: Daniel Golle <daniel@makrotopia.org>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/1569290b21cc787a424469ed74456a7e976b102d.1715084326.git.daniel@makrotopia.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>