checkpatch: suggest pr_<level> over printk(KERN_<LEVEL>

Suggest the shorter pr_<level> instead of printk(KERN_<LEVEL>.

Prefer to use pr_<level> over bare printks.
Prefer to use pr_warn over pr_warning.

Signed-off-by: Joe Perches <joe@perches.com>
Cc: Andy Whitcroft <apw@shadowen.org>
Cc: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

scripts/checkpatch.pl

@@ -2382,6 +2382,19 @@ sub process {
 			}
 		}
 
+		if ($line =~ /\bprintk\s*\(\s*KERN_([A-Z]+)/) {
+			my $orig = $1;
+			my $level = lc($orig);
+			$level = "warn" if ($level eq "warning");
+			WARN("PREFER_PR_LEVEL",
+			     "Prefer pr_$level(... to printk(KERN_$1, ...\n" . $herecurr);
+		}
+
+		if ($line =~ /\bpr_warning\s*\(/) {
+			WARN("PREFER_PR_LEVEL",
+			     "Prefer pr_warn(... to pr_warning(...\n" . $herecurr);
+		}
+
 # function brace can't be on same line, except for #defines of do while,
 # or if closed on same line
 		if (($line=~/$Type\s*$Ident\(.*\).*\s{/) and