agp: use semicolons rather than commas to separate statements

Replace commas with semicolons.  What is done is essentially described by
the following Coccinelle semantic patch (http://coccinelle.lip6.fr/

):

// <smpl>
@@ expression e1,e2; @@
e1
-,
+;
e2
... when any
// </smpl>

Signed-off-by: Julia Lawall <Julia.Lawall@inria.fr>
Signed-off-by: Dave Airlie <airlied@redhat.com>