tools: checkpatch: Restore 'debug' and 'printf' to logFunctions list

The 'debug' and 'printf' functions were previously added to the list of
logFunctions in commit 0cab4211 ("checkpatch.pl: Add 'debug' to
the list of logFunctions") and commit 397bfd46 ("checkpatch.pl:
Add 'printf' to logFunctions") but these additions were lost when newer
versions of checkpatch were pulled in from the upstream Linux
kernel version.

This restores them so that you don't end up in a situation where
checkpatch will give a warning for "quoted string split across lines"
which you cannot fix without getting a warning for "line over 80
characters" instead.

Signed-off-by: James Byrne <james.byrne@origamienergy.com>