coding-style.rst: trivial: fix location of driver model macros

The dev_printk()-like functions moved to include/linux/dev_print.h in
commit af628aae

 ("device.h: move dev_printk()-like functions to
dev_printk.h").

Signed-off-by: Trevor Woerner <twoerner@gmail.com>
Reviewed-by: Shuah Khan <skhan@linuxfoundation.org>
Reviewed-by: Miguel Ojeda <ojeda@kernel.org>
Link: https://lore.kernel.org/r/20210423184012.39300-1-twoerner@gmail.com
Signed-off-by: Jonathan Corbet <corbet@lwn.net>