gitweb: Fix Atom feed <logo>: it is $logo, not $logo_url

Fix contents of Atom feed <logo> element; it should be URL of $logo, not URL pointed by logo link.

---
Do anyone use Atom feed logo? This error was from the beginning of Atom feed generation in git.git version of gitweb, and nobody complained.

I wonder why it is <logo>URL</logo>, and not <logo href="URL" />...

 gitweb/gitweb.perl |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

index 093bd72..ffe8ce1 100755
@@ -4282,7 +4282,7 @@ XML
 		}
 		if (defined $logo_url) {
 			# not twice as wide as tall: 72 x 27 pixels
-			print "<logo>" . esc_url($logo_url) . "</logo>\n";
+			print "<logo>" . esc_url($logo) . "</logo>\n";
 		}
 		if (! %latest_date) {
 			# dummy date to keep the feed valid until commits trickle in:

1.4.4.1