checkpatch: add fix option for LOGICAL_CONTINUATIONS

Currently, checkpatch warns if logical continuations are placed at the
start of a line and not at the end of previous line.

E.g., running checkpatch on commit 3485507f ("staging: bcm2835-camera:
Reduce length of enum names") reports:

  CHECK:LOGICAL_CONTINUATIONS: Logical continuations should be on the previous line
  +	if (!ret
  +	    && camera_port ==

Provide a simple fix by inserting logical operator at the last
non-comment, non-whitespace char of the previous line and removing from
current line, if both the lines are additions(ie start with '+')

Link: https://lkml.kernel.org/r/20201123102818.24364-1-yashsri421@gmail.comSigned-off-by: Aditya Srivastava <yashsri421@gmail.com>
Acked-by: Joe Perches <joe@perches.com>
Cc: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

scripts/checkpatch.pl

@@ -3545,8 +3545,16 @@ sub process {
 
 # check for && or || at the start of a line
 		if ($rawline =~ /^\+\s*(&&|\|\|)/) {
-			CHK("LOGICAL_CONTINUATIONS",
-			    "Logical continuations should be on the previous line\n" . $hereprev);
+			my $operator = $1;
+			if (CHK("LOGICAL_CONTINUATIONS",
+				"Logical continuations should be on the previous line\n" . $hereprev) &&
+			    $fix && $prevrawline =~ /^\+/) {
+				# insert logical operator at last non-comment, non-whitepsace char on previous line
+				$prevline =~ /[\s$;]*$/;
+				my $line_end = substr($prevrawline, $-[0]);
+				$fixed[$fixlinenr - 1] =~ s/\Q$line_end\E$/ $operator$line_end/;
+				$fixed[$fixlinenr] =~ s/\Q$operator\E\s*//;
+			}
 		}
 
 # check indentation starts on a tab stop