clk: socfpga: stratix10: fix rate caclulationg for cnt_clks

Checking bypass_reg is incorrect for calculating the cnt_clk rates.
Instead we should be checking that there is a proper hardware register
that holds the clock divider.

Cc: stable@vger.kernel.org
Signed-off-by: Dinh Nguyen <dinguyen@kernel.org>
Link: https://lkml.kernel.org/r/20190814153014.12962-1-dinguyen@kernel.org
Signed-off-by: Stephen Boyd <sboyd@kernel.org>