Since commit f8c55dc ("MIPS: use generic dma noncoherent ops for
simple noncoherent platforms") changed MIPS dma handling, the mmc
driver fails because it doesn't have a dma mask is set.
So set the correct dma mask.
Signed-off-by: NeilBrown <neil@brown.name>
Signed-off-by: DENG Qingfang <dengqf6@mail2.sysu.edu.cn>