mips: dts: ralink: mt7621: define each reset as an item

Each item of the resets property should define a reset. Split the item with
two resets on the ethernet node into two separate items.

Sort the items of the clocks property to the same line as a trivial change.

Signed-off-by: Arınç ÜNAL <arinc.unal@arinc9.com>
Acked-by: Sergio Paracuellos <sergio.paracuellos@gmail.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>