MAINTAINERS: add myself as maintainer for public I/O interfaces

The "PUBLIC I/O INTERFACES AND PV DRIVERS DESIGNS" section of the
MAINTAINERS file lists Konrad as the only maintainer. Add myself for
helping him to review patches.

Signed-off-by: Juergen Gross <jgross@suse.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

MAINTAINERS

@@ -329,6 +329,7 @@ F:	xen/include/acpi/cpufreq/
 
 PUBLIC I/O INTERFACES AND PV DRIVERS DESIGNS
 M:	Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
+M:	Juergen Gross <jgross@suse.com>
 S:	Supported
 F:	xen/include/public/io/