The sunxi mmc driver tries to calculate a dma address by using pointer
arithmetic, which causes a warning when dma_addr_t is wider than a pointer:
drivers/mmc/host/sunxi-mmc.c: In function 'sunxi_mmc_init_idma_des':
drivers/mmc/host/sunxi-mmc.c:296:35: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast]
struct sunxi_idma_des *pdes_pa = (struct sunxi_idma_des *)host->sg_dma;
^
To avoid this warning and to simplify the logic, this changes
the code to avoid the cast and calculate the correct address
manually. The behavior should be unchanged.