ati_pcigart: fix printk format warning

Fix ati_pcigart printk format warning:

drivers/gpu/drm/ati_pcigart.c:115: warning: format '%Lx' expects type 'long long unsigned int', but argument 3 has type 'dma_addr_t'

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Cc: Zhenyu Wang <zhenyuw@linux.intel.com>
Cc: Dave Airlie <airlied@linux.ie>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Dave Airlie <airlied@redhat.com>