DMA addresses are not pointers, so don't treat them as such. Avoids
compiler warnings when using 64-bit DMA addresses on a 32-bit system.
Signed-off-by: Pierre Ossman <drzeus@drzeus.cx>
 
        dma_unmap_single(mmc_dev(host->mmc), host->dma_addr,
                WBSD_DMA_SIZE, DMA_BIDIRECTIONAL);
-       host->dma_addr = (dma_addr_t)NULL;
+       host->dma_addr = 0;
 
        kfree(host->dma_buffer);
        host->dma_buffer = NULL;
 
        host->dma = -1;
        host->dma_buffer = NULL;
-       host->dma_addr = (dma_addr_t)NULL;
+       host->dma_addr = 0;
 }
 
 /*