Change struct pat data_pa type to dma_addr_t

The single one use-case for data_pa member of the struct pat is to carry a value of dma_addr_t type.
This patch solves the following compilation error:

../drivers/gpu/drm/omapdrm/omap_dmm_tiler.c: In function 'dmm_txn_append':
../drivers/gpu/drm/omapdrm/omap_dmm_tiler.c:226:2: error: passing argument 3 of 'alloc_dma' from incompatible pointer type [-Werror]
  data = alloc_dma(txn, 4*i, &pat->data_pa);
  ^
../drivers/gpu/drm/omapdrm/omap_dmm_tiler.c:77:14: note: expected 'dma_addr_t *' but argument is of type 'uint32_t *'
 static void *alloc_dma(struct dmm_txn *txn, size_t sz, dma_addr_t *pa)
              ^

Signed-off-by: Matwey V. Kornilov <matwey@sai.msu.ru>