ARM: socfpga: dts: fix s2f_* clock name

The s2f_* clocks are called h2f_* in the datasheets.
Rename them accordingly in the socfpga.dtsi.

Signed-off-by: Steffen Trumtrar <s.trumtrar@pengutronix.de>
Signed-off-by: Dinh Nguyen <dinguyen@altera.com>