checkstack: fix printed address

All addresses printed by checkstack have an extra incorrect 0 appended at
the end.

This was introduced with commit 677f1410 ("scripts/checkstack.pl: don't
display $dre as different entity"): since then the address is taken from
the line which contains the function name, instead of the line which
contains stack consumption. E.g. on s390:

0000000000100a30 <do_one_initcall>:
...
  100a44:       e3 f0 ff 70 ff 71       lay     %r15,-144(%r15)

So the used regex which matches spaces and hexadecimal numbers to extract
an address now matches a different substring. Subsequently replacing spaces
with 0 appends a zero at the and, instead of replacing leading spaces.

Fix this by using the proper regex, and simplify the code a bit.

Link: https://lkml.kernel.org/r/20231120183719.2188479-2-hca@linux.ibm.com
Fixes: 677f1410 ("scripts/checkstack.pl: don't display $dre as different entity")
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Cc: Maninder Singh <maninder1.s@samsung.com>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Vaneet Narang <v.narang@samsung.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

scripts/checkstack.pl

@@ -139,15 +139,11 @@ $total_size = 0;
 while (my $line = <STDIN>) {
 	if ($line =~ m/$funcre/) {
 		$func = $1;
-		next if $line !~ m/^($xs*)/;
+		next if $line !~ m/^($x*)/;
 		if ($total_size > $min_stack) {
 			push @stack, "$intro$total_size\n";
 		}
-
-		$addr = $1;
-		$addr =~ s/ /0/g;
-		$addr = "0x$addr";
-
+		$addr = "0x$1";
 		$intro = "$addr $func [$file]:";
 		my $padlen = 56 - length($intro);
 		while ($padlen > 0) {