dt/bindings: reformat micrel eth-phy documentation

Reduce indentation of Micrel PHY binding documentations somewhat.

Also fix "reference input clock" typo while at it.

Cc: devicetree@vger.kernel.org
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>