arm64: dts: mediatek: mt7986: drop "#reset-cells" from Ethernet controller

Ethernet block doesn't include or act as a reset controller.
Documentation also doesn't document "#reset-cells" for it.

This fixes:
arch/arm64/boot/dts/mediatek/mt7986a-bananapi-bpi-r3.dtb: ethernet@15100000: Unevaluated properties are not allowed ('#reset-cells' was unexpected)
        from schema $id: http://devicetree.org/schemas/net/mediatek,net.yaml#

Fixes: 082ff36 ("arm64: dts: mediatek: mt7986: introduce ethernet nodes")
Cc: Lorenzo Bianconi <lorenzo@kernel.org>
Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://lore.kernel.org/r/20240213053739.14387-2-zajec5@gmail.com
Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>

Author: Rafał Miłecki

arch/arm64/boot/dts/mediatek/mt7986a.dtsi

@@ -554,7 +554,6 @@
 					  <&topckgen CLK_TOP_SGM_325M_SEL>;
 			assigned-clock-parents = <&apmixedsys CLK_APMIXED_NET2PLL>,
 						 <&apmixedsys CLK_APMIXED_SGMPLL>;
-			#reset-cells = <1>;
 			#address-cells = <1>;
 			#size-cells = <0>;
 			mediatek,ethsys = <&ethsys>;