aw_clk_nm: fix incorrect use of abs()

[avg]

Summary

abs() takes a (signed) int as input.
Instead, it was used with unsigned 64-bit integers.

[manu]

Thanks, I had no time to fix this.
abs is used on more clock drivers for allwinner so I think that adding the inline function to aw_clk.h would be better.

[avg]

If this function to become more visible, do you think distance is still a good name?
Maybe something like freq_diff? Something else?
Thanks!

[avg]

If this function to become more visible, do you think distance is still a good name?
Maybe something like freq_diff? Something else?
Thanks!

[avg]

If this function to become more visible, do you think distance is still a good name?
Maybe something like freq_diff? Something else?
Thanks!

[avg]

expose clk_freq_diff to other clk drivers