i2c: uniphier(-f): remove all dev_dbg()

I have fixed various bugs, and these drivers are (I hope) pretty
stable now. Remove all dev_dbg() for code clean-up.

If I end up with debugging the drivers again, I will locally revert
this commit. I no longer need the debug code in upstream.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>