dt-bindings: net: dsa: mediatek,mt7530: change some descriptions to literal

The line endings must be preserved on gpio-controller, io-supply, and
reset-gpios properties to look proper when the YAML file is parsed.

Currently it's interpreted as a single line when parsed. Change the style
of the description of these properties to literal style to preserve the
line endings.

Signed-off-by: Arınç ÜNAL <arinc.unal@arinc9.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>