clk: fractional-divider: Use bit operations consistently

clk: fractional-divider: Use bit operations consistently

Use BIT() where makes sense. This alings usage of bit operations
in the same pieces of code. Moreover, strictly speaking by the
letter of the C standard, left shift of 1 by 31 bits is UB (undefined
behaviour), switching to BIT() addresses that as well.

Signed-off-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Link: https://lore.kernel.org/r/20240303120732.240355-1-andy.shevchenko@gmail.com
Reviewed-by: Chen-Yu Tsai <wenst@chromium.org>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>