checkpatch: Remove awareness of uninitialized_var() macro

Using uninitialized_var() is dangerous as it papers over real bugs[1]
(or can in the future), and suppresses unrelated compiler warnings
(e.g. "unused variable"). If the compiler thinks it is uninitialized,
either simply initialize the variable or make compiler changes.

In preparation for removing[2] the[3] macro[4], partially revert
commit 16b7f3c8 ("checkpatch: avoid warning about uninitialized_var()")
and remove all remaining mentions of uninitialized_var().

[1] https://lore.kernel.org/lkml/20200603174714.192027-1-glider@google.com/
[2] https://lore.kernel.org/lkml/CA+55aFw+Vbj0i=1TGqCR5vQkCzWJ0QxK6CernOU6eedsudAixw@mail.gmail.com/
[3] https://lore.kernel.org/lkml/CA+55aFwgbgqhbp1fkxvRKEpzyR5J8n1vKT1VZdz9knmPuXhOeg@mail.gmail.com/
[4] https://lore.kernel.org/lkml/CA+55aFz2500WfbKXAx8s67wrm9=yVJu65TpLgN_ybYNv0VEOKA@mail.gmail.com/Signed-off-by: Kees Cook <keescook@chromium.org>

scripts/checkpatch.pl

@@ -840,7 +840,6 @@ our $FuncArg = qr{$Typecast{0,1}($LvalOrFunc|$Constant|$String)};
 our $declaration_macros = qr{(?x:
 	(?:$Storage\s+)?(?:[A-Z_][A-Z0-9]*_){0,2}(?:DEFINE|DECLARE)(?:_[A-Z0-9]+){1,6}\s*\(|
 	(?:$Storage\s+)?[HLP]?LIST_HEAD\s*\(|
-	(?:$Storage\s+)?${Type}\s+uninitialized_var\s*\(|
 	(?:SKCIPHER_REQUEST|SHASH_DESC|AHASH_REQUEST)_ON_STACK\s*\(
 )};
 
@@ -6330,8 +6329,7 @@ sub process {
 			if (defined $cond) {
 				substr($s, 0, length($cond), '');
 			}
-			if ($s =~ /^\s*;/ &&
-			    $function_name ne 'uninitialized_var')
+			if ($s =~ /^\s*;/)
 			{
 				WARN("AVOID_EXTERNS",
 				     "externs should be avoided in .c files\n" .  $herecurr);
@@ -6350,17 +6348,13 @@ sub process {
 		}
 
 # check for function declarations that have arguments without identifier names
-# while avoiding uninitialized_var(x)
 		if (defined $stat &&
-		    $stat =~ /^.\s*(?:extern\s+)?$Type\s*(?:($Ident)|\(\s*\*\s*$Ident\s*\))\s*\(\s*([^{]+)\s*\)\s*;/s &&
-		    (!defined($1) ||
-		     (defined($1) && $1 ne "uninitialized_var")) &&
-		     $2 ne "void") {
-			my $args = trim($2);
+		    $stat =~ /^.\s*(?:extern\s+)?$Type\s*(?:$Ident|\(\s*\*\s*$Ident\s*\))\s*\(\s*([^{]+)\s*\)\s*;/s &&
+		    $1 ne "void") {
+			my $args = trim($1);
 			while ($args =~ m/\s*($Type\s*(?:$Ident|\(\s*\*\s*$Ident?\s*\)\s*$balanced_parens)?)/g) {
 				my $arg = trim($1);
-				if ($arg =~ /^$Type$/ &&
-					$arg !~ /enum\s+$Ident$/) {
+				if ($arg =~ /^$Type$/ && $arg !~ /enum\s+$Ident$/) {
 					WARN("FUNCTION_ARGUMENTS",
 					     "function definition argument '$arg' should also have an identifier name\n" . $herecurr);
 				}