[media] ti-vpe: Fix typecast

Addresses have the same size of unsigned long, and not u32.

That removes a warning on 64 bits compilation:
drivers/media//platform/ti-vpe/vpdma.c:332:11: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast]
  WARN_ON(((u32) buf->addr & VPDMA_DESC_ALIGN) != 0);
           ^
include/asm-generic/bug.h:86:25: note: in definition of macro ‘WARN_ON’
  int __ret_warn_on = !!(condition);    \
                         ^

Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>