i2c: core: remove outdated DEBUG output

The usefulness of this debug output is questionable. It covers only
direct i2c_transfer calls and no SMBUS calls, neither direct nor
emulated ones. And the latter one is largely used in the kernel, so a
lot of stuff is missed. False positives are also generated in case the
locking later fails. Also, we have a proper tracing mechanism for all
these kinds of transfers in place for years now. Remove this old one.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Acked-by: Peter Rosin <peda@axentia.se>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>