clk: socfpga: stratix10: fix naming convention for the fixed-clocks

The fixed clocks in the DTS file have a hyphen, but the clock driver has
the fixed clocks using underbar. Thus the clock driver cannot detect the
other fixed clocks correctly. Change the fixed clock names to a hyphen.

Fixes: 07afb8db

 ("clk: socfpga: stratix10: add clock driver for
Stratix10 platform")
Cc: linux-stable@vger.kernel.org
Signed-off-by: Dinh Nguyen <dinguyen@kernel.org>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>