kernel-doc: Allow anonymous enum

In C is a valid construction to have an anonymous enumerator.

Though we have now:

  drivers/pinctrl/intel/pinctrl-intel.c:240: error: Cannot parse enum!

Support it in the kernel-doc script.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

scripts/kernel-doc

@@ -1245,7 +1245,7 @@ sub dump_enum($$) {
     # strip #define macros inside enums
     $x =~ s@#\s*((define|ifdef)\s+|endif)[^;]*;@@gos;
 
-    if ($x =~ /enum\s+(\w+)\s*\{(.*)\}/) {
+    if ($x =~ /enum\s+(\w*)\s*\{(.*)\}/) {
 	$declaration_name = $1;
 	my $members = $2;
 	my %_members;