drivers/char/agp/parisc-agp.c: eliminate memory leak

alloc_pci_dev allocates some memory, so that memory should be freed before
leaving the function in an error case.

A simplified version of the semantic match that finds this problem is:
(http://coccinelle.lip6.fr/

)

// <smpl>
@r exists@
local idexpression x;
expression E;
identifier f1;
iterator I;
@@

x = alloc_pci_dev(...);
<... when != x
     when != true (x == NULL || ...)
     when != if (...) { <+...x...+> }
     when != I (...) { <+...x...+> }
(
 x == NULL
|
 x == E
|
 x->f1
)
...>
* return ...;
// </smpl>

Signed-off-by: Julia Lawall <julia@diku.dk>
Dan Carpenter <error27@gmail.com>
Dave Airlie <airlied@linux.ie>
Cc: Helge Deller <deller@gmx.de>
Cc: "James E.J. Bottomley" <jejb@parisc-linux.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Kyle McMartin <kyle@redhat.com>