MAINTAINERS: update xgifb maintainer's e-mail address

All patches sent to the maintainer address bounce:

   Diagnostic-Code: smtp; 550 5.1.1 <apatard@mandriva.com>: Recipient address
       rejected: User unknown in virtual mailbox table

The address found in drivers/staging/xgifb/TODO seems to work better.
Signed-off-by: Aaro Koskinen <aaro.koskinen@iki.fi>
Cc: arnaud.patard@rtp-net.org
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

MAINTAINERS

@@ -6410,7 +6410,7 @@ S:	Odd Fixes
 F:	drivers/staging/winbond/
 
 STAGING - XGI Z7,Z9,Z11 PCI DISPLAY DRIVER
-M:	Arnaud Patard <apatard@mandriva.com>
+M:	Arnaud Patard <arnaud.patard@rtp-net.org>
 S:	Odd Fixes
 F:	drivers/staging/xgifb/