clk: socfpga: stratix10: add clock driver for Stratix10 platform

Add a clock driver for the Stratix10 SoC. The driver is similar to the
Cyclone5/Arria10 platforms, with the exception that this driver only uses
one single clock binding.

Signed-off-by: Dinh Nguyen <dinguyen@kernel.org>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>