mmc: sirf: fix the capbility to support DDR50

According to hardware spec, validate DDR50 mode
for SDXC.

Signed-off-by: Weijun Yang <york.yang@csr.com>
Signed-off-by: Barry Song <Baohua.Song@csr.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
1 file changed